fs/btrfs/scrub.c

   1 /*
   2  * Copyright (C) 2011, 2012 STRATO.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/ratelimit.h>
  21 #include "ctree.h"
  22 #include "volumes.h"
  23 #include "disk-io.h"
  24 #include "ordered-data.h"
  25 #include "transaction.h"
  26 #include "backref.h"
  27 #include "extent_io.h"
  28 #include "dev-replace.h"
  29 #include "check-integrity.h"
  30 #include "rcu-string.h"
  31 #include "raid56.h"
  32
  33 /*
  34  * This is only the first step towards a full-features scrub. It reads all
  35  * extent and super block and verifies the checksums. In case a bad checksum
  36  * is found or the extent cannot be read, good data will be written back if
  37  * any can be found.
  38  *
  39  * Future enhancements:
  40  *  - In case an unrepairable extent is encountered, track which files are
  41  *    affected and report them
  42  *  - track and record media errors, throw out bad devices
  43  *  - add a mode to also read unallocated space
  44  */
  45
  46 struct scrub_block;
  47 struct scrub_ctx;
  48
  49 /*
  50  * the following three values only influence the performance.
  51  * The last one configures the number of parallel and outstanding I/O
  52  * operations. The first two values configure an upper limit for the number
  53  * of (dynamically allocated) pages that are added to a bio.
  54  */
  55 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  56 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  57 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  58
  59 /*
  60  * the following value times PAGE_SIZE needs to be large enough to match the
  61  * largest node/leaf/sector size that shall be supported.
  62  * Values larger than BTRFS_STRIPE_LEN are not supported.
  63  */
  64 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  65
  66 struct scrub_recover {
  67         atomic_t                refs;
  68         struct btrfs_bio        *bbio;
  69         u64                     map_length;
  70 };
  71
  72 struct scrub_page {
  73         struct scrub_block      *sblock;
  74         struct page             *page;
  75         struct btrfs_device     *dev;
  76         struct list_head        list;
  77         u64                     flags;  /* extent flags */
  78         u64                     generation;
  79         u64                     logical;
  80         u64                     physical;
  81         u64                     physical_for_dev_replace;
  82         atomic_t                refs;
  83         struct {
  84                 unsigned int    mirror_num:8;
  85                 unsigned int    have_csum:1;
  86                 unsigned int    io_error:1;
  87         };
  88         u8                      csum[BTRFS_CSUM_SIZE];
  89
  90         struct scrub_recover    *recover;
  91 };
  92
  93 struct scrub_bio {
  94         int                     index;
  95         struct scrub_ctx        *sctx;
  96         struct btrfs_device     *dev;
  97         struct bio              *bio;
  98         int                     err;
  99         u64                     logical;
 100         u64                     physical;
 101 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
 102         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
 103 #else
 104         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
 105 #endif
 106         int                     page_count;
 107         int                     next_free;
 108         struct btrfs_work       work;
 109 };
 110
 111 struct scrub_block {
 112         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 113         int                     page_count;
 114         atomic_t                outstanding_pages;
 115         atomic_t                refs; /* free mem on transition to zero */
 116         struct scrub_ctx        *sctx;
 117         struct scrub_parity     *sparity;
 118         struct {
 119                 unsigned int    header_error:1;
 120                 unsigned int    checksum_error:1;
 121                 unsigned int    no_io_error_seen:1;
 122                 unsigned int    generation_error:1; /* also sets header_error */
 123
 124                 /* The following is for the data used to check parity */
 125                 /* It is for the data with checksum */
 126                 unsigned int    data_corrected:1;
 127         };
 128         struct btrfs_work       work;
 129 };
 130
 131 /* Used for the chunks with parity stripe such RAID5/6 */
 132 struct scrub_parity {
 133         struct scrub_ctx        *sctx;
 134
 135         struct btrfs_device     *scrub_dev;
 136
 137         u64                     logic_start;
 138
 139         u64                     logic_end;
 140
 141         int                     nsectors;
 142
 143         int                     stripe_len;
 144
 145         atomic_t                refs;
 146
 147         struct list_head        spages;
 148
 149         /* Work of parity check and repair */
 150         struct btrfs_work       work;
 151
 152         /* Mark the parity blocks which have data */
 153         unsigned long           *dbitmap;
 154
 155         /*
 156          * Mark the parity blocks which have data, but errors happen when
 157          * read data or check data
 158          */
 159         unsigned long           *ebitmap;
 160
 161         unsigned long           bitmap[0];
 162 };
 163
 164 struct scrub_wr_ctx {
 165         struct scrub_bio *wr_curr_bio;
 166         struct btrfs_device *tgtdev;
 167         int pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 168         atomic_t flush_all_writes;
 169         struct mutex wr_lock;
 170 };
 171
 172 struct scrub_ctx {
 173         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 174         struct btrfs_root       *dev_root;
 175         int                     first_free;
 176         int                     curr;
 177         atomic_t                bios_in_flight;
 178         atomic_t                workers_pending;
 179         spinlock_t              list_lock;
 180         wait_queue_head_t       list_wait;
 181         u16                     csum_size;
 182         struct list_head        csum_list;
 183         atomic_t                cancel_req;
 184         int                     readonly;
 185         int                     pages_per_rd_bio;
 186         u32                     sectorsize;
 187         u32                     nodesize;
 188
 189         int                     is_dev_replace;
 190         struct scrub_wr_ctx     wr_ctx;
 191
 192         /*
 193          * statistics
 194          */
 195         struct btrfs_scrub_progress stat;
 196         spinlock_t              stat_lock;
 197
 198         /*
 199          * Use a ref counter to avoid use-after-free issues. Scrub workers
 200          * decrement bios_in_flight and workers_pending and then do a wakeup
 201          * on the list_wait wait queue. We must ensure the main scrub task
 202          * doesn't free the scrub context before or while the workers are
 203          * doing the wakeup() call.
 204          */
 205         atomic_t                refs;
 206 };
 207
 208 struct scrub_fixup_nodatasum {
 209         struct scrub_ctx        *sctx;
 210         struct btrfs_device     *dev;
 211         u64                     logical;
 212         struct btrfs_root       *root;
 213         struct btrfs_work       work;
 214         int                     mirror_num;
 215 };
 216
 217 struct scrub_nocow_inode {
 218         u64                     inum;
 219         u64                     offset;
 220         u64                     root;
 221         struct list_head        list;
 222 };
 223
 224 struct scrub_copy_nocow_ctx {
 225         struct scrub_ctx        *sctx;
 226         u64                     logical;
 227         u64                     len;
 228         int                     mirror_num;
 229         u64                     physical_for_dev_replace;
 230         struct list_head        inodes;
 231         struct btrfs_work       work;
 232 };
 233
 234 struct scrub_warning {
 235         struct btrfs_path       *path;
 236         u64                     extent_item_size;
 237         const char              *errstr;
 238         sector_t                sector;
 239         u64                     logical;
 240         struct btrfs_device     *dev;
 241 };
 242
 243 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 244 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 245 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
 246 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
 247 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 248 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 249                                      struct scrub_block *sblocks_for_recheck);
 250 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 251                                 struct scrub_block *sblock,
 252                                 int retry_failed_mirror);
 253 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 254 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 255                                              struct scrub_block *sblock_good);
 256 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 257                                             struct scrub_block *sblock_good,
 258                                             int page_num, int force_write);
 259 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 260 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 261                                            int page_num);
 262 static int scrub_checksum_data(struct scrub_block *sblock);
 263 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 264 static int scrub_checksum_super(struct scrub_block *sblock);
 265 static void scrub_block_get(struct scrub_block *sblock);
 266 static void scrub_block_put(struct scrub_block *sblock);
 267 static void scrub_page_get(struct scrub_page *spage);
 268 static void scrub_page_put(struct scrub_page *spage);
 269 static void scrub_parity_get(struct scrub_parity *sparity);
 270 static void scrub_parity_put(struct scrub_parity *sparity);
 271 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 272                                     struct scrub_page *spage);
 273 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 274                        u64 physical, struct btrfs_device *dev, u64 flags,
 275                        u64 gen, int mirror_num, u8 *csum, int force,
 276                        u64 physical_for_dev_replace);
 277 static void scrub_bio_end_io(struct bio *bio);
 278 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 279 static void scrub_block_complete(struct scrub_block *sblock);
 280 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 281                                u64 extent_logical, u64 extent_len,
 282                                u64 *extent_physical,
 283                                struct btrfs_device **extent_dev,
 284                                int *extent_mirror_num);
 285 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
 286                               struct scrub_wr_ctx *wr_ctx,
 287                               struct btrfs_fs_info *fs_info,
 288                               struct btrfs_device *dev,
 289                               int is_dev_replace);
 290 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx);
 291 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 292                                     struct scrub_page *spage);
 293 static void scrub_wr_submit(struct scrub_ctx *sctx);
 294 static void scrub_wr_bio_end_io(struct bio *bio);
 295 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 296 static int write_page_nocow(struct scrub_ctx *sctx,
 297                             u64 physical_for_dev_replace, struct page *page);
 298 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
 299                                       struct scrub_copy_nocow_ctx *ctx);
 300 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 301                             int mirror_num, u64 physical_for_dev_replace);
 302 static void copy_nocow_pages_worker(struct btrfs_work *work);
 303 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 304 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 305 static void scrub_put_ctx(struct scrub_ctx *sctx);
 306
 307
 308 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 309 {
 310         atomic_inc(&sctx->refs);
 311         atomic_inc(&sctx->bios_in_flight);
 312 }
 313
 314 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 315 {
 316         atomic_dec(&sctx->bios_in_flight);
 317         wake_up(&sctx->list_wait);
 318         scrub_put_ctx(sctx);
 319 }
 320
 321 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 322 {
 323         while (atomic_read(&fs_info->scrub_pause_req)) {
 324                 mutex_unlock(&fs_info->scrub_lock);
 325                 wait_event(fs_info->scrub_pause_wait,
 326                    atomic_read(&fs_info->scrub_pause_req) == 0);
 327                 mutex_lock(&fs_info->scrub_lock);
 328         }
 329 }
 330
 331 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 332 {
 333         atomic_inc(&fs_info->scrubs_paused);
 334         wake_up(&fs_info->scrub_pause_wait);
 335 }
 336
 337 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 338 {
 339         mutex_lock(&fs_info->scrub_lock);
 340         __scrub_blocked_if_needed(fs_info);
 341         atomic_dec(&fs_info->scrubs_paused);
 342         mutex_unlock(&fs_info->scrub_lock);
 343
 344         wake_up(&fs_info->scrub_pause_wait);
 345 }
 346
 347 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 348 {
 349         scrub_pause_on(fs_info);
 350         scrub_pause_off(fs_info);
 351 }
 352
 353 /*
 354  * used for workers that require transaction commits (i.e., for the
 355  * NOCOW case)
 356  */
 357 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
 358 {
 359         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 360
 361         atomic_inc(&sctx->refs);
 362         /*
 363          * increment scrubs_running to prevent cancel requests from
 364          * completing as long as a worker is running. we must also
 365          * increment scrubs_paused to prevent deadlocking on pause
 366          * requests used for transactions commits (as the worker uses a
 367          * transaction context). it is safe to regard the worker
 368          * as paused for all matters practical. effectively, we only
 369          * avoid cancellation requests from completing.
 370          */
 371         mutex_lock(&fs_info->scrub_lock);
 372         atomic_inc(&fs_info->scrubs_running);
 373         atomic_inc(&fs_info->scrubs_paused);
 374         mutex_unlock(&fs_info->scrub_lock);
 375
 376         /*
 377          * check if @scrubs_running=@scrubs_paused condition
 378          * inside wait_event() is not an atomic operation.
 379          * which means we may inc/dec @scrub_running/paused
 380          * at any time. Let's wake up @scrub_pause_wait as
 381          * much as we can to let commit transaction blocked less.
 382          */
 383         wake_up(&fs_info->scrub_pause_wait);
 384
 385         atomic_inc(&sctx->workers_pending);
 386 }
 387
 388 /* used for workers that require transaction commits */
 389 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
 390 {
 391         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 392
 393         /*
 394          * see scrub_pending_trans_workers_inc() why we're pretending
 395          * to be paused in the scrub counters
 396          */
 397         mutex_lock(&fs_info->scrub_lock);
 398         atomic_dec(&fs_info->scrubs_running);
 399         atomic_dec(&fs_info->scrubs_paused);
 400         mutex_unlock(&fs_info->scrub_lock);
 401         atomic_dec(&sctx->workers_pending);
 402         wake_up(&fs_info->scrub_pause_wait);
 403         wake_up(&sctx->list_wait);
 404         scrub_put_ctx(sctx);
 405 }
 406
 407 static void scrub_free_csums(struct scrub_ctx *sctx)
 408 {
 409         while (!list_empty(&sctx->csum_list)) {
 410                 struct btrfs_ordered_sum *sum;
 411                 sum = list_first_entry(&sctx->csum_list,
 412                                        struct btrfs_ordered_sum, list);
 413                 list_del(&sum->list);
 414                 kfree(sum);
 415         }
 416 }
 417
 418 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 419 {
 420         int i;
 421
 422         if (!sctx)
 423                 return;
 424
 425         scrub_free_wr_ctx(&sctx->wr_ctx);
 426
 427         /* this can happen when scrub is cancelled */
 428         if (sctx->curr != -1) {
 429                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 430
 431                 for (i = 0; i < sbio->page_count; i++) {
 432                         WARN_ON(!sbio->pagev[i]->page);
 433                         scrub_block_put(sbio->pagev[i]->sblock);
 434                 }
 435                 bio_put(sbio->bio);
 436         }
 437
 438         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 439                 struct scrub_bio *sbio = sctx->bios[i];
 440
 441                 if (!sbio)
 442                         break;
 443                 kfree(sbio);
 444         }
 445
 446         scrub_free_csums(sctx);
 447         kfree(sctx);
 448 }
 449
 450 static void scrub_put_ctx(struct scrub_ctx *sctx)
 451 {
 452         if (atomic_dec_and_test(&sctx->refs))
 453                 scrub_free_ctx(sctx);
 454 }
 455
 456 static noinline_for_stack
 457 struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 458 {
 459         struct scrub_ctx *sctx;
 460         int             i;
 461         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
 462         int ret;
 463
 464         sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 465         if (!sctx)
 466                 goto nomem;
 467         atomic_set(&sctx->refs, 1);
 468         sctx->is_dev_replace = is_dev_replace;
 469         sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 470         sctx->curr = -1;
 471         sctx->dev_root = dev->dev_root;
 472         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 473                 struct scrub_bio *sbio;
 474
 475                 sbio = kzalloc(sizeof(*sbio), GFP_KERNEL);
 476                 if (!sbio)
 477                         goto nomem;
 478                 sctx->bios[i] = sbio;
 479
 480                 sbio->index = i;
 481                 sbio->sctx = sctx;
 482                 sbio->page_count = 0;
 483                 btrfs_init_work(&sbio->work, btrfs_scrub_helper,
 484                                 scrub_bio_end_io_worker, NULL, NULL);
 485
 486                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 487                         sctx->bios[i]->next_free = i + 1;
 488                 else
 489                         sctx->bios[i]->next_free = -1;
 490         }
 491         sctx->first_free = 0;
 492         sctx->nodesize = dev->dev_root->nodesize;
 493         sctx->sectorsize = dev->dev_root->sectorsize;
 494         atomic_set(&sctx->bios_in_flight, 0);
 495         atomic_set(&sctx->workers_pending, 0);
 496         atomic_set(&sctx->cancel_req, 0);
 497         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 498         INIT_LIST_HEAD(&sctx->csum_list);
 499
 500         spin_lock_init(&sctx->list_lock);
 501         spin_lock_init(&sctx->stat_lock);
 502         init_waitqueue_head(&sctx->list_wait);
 503
 504         ret = scrub_setup_wr_ctx(sctx, &sctx->wr_ctx, fs_info,
 505                                  fs_info->dev_replace.tgtdev, is_dev_replace);
 506         if (ret) {
 507                 scrub_free_ctx(sctx);
 508                 return ERR_PTR(ret);
 509         }
 510         return sctx;
 511
 512 nomem:
 513         scrub_free_ctx(sctx);
 514         return ERR_PTR(-ENOMEM);
 515 }
 516
 517 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 518                                      void *warn_ctx)
 519 {
 520         u64 isize;
 521         u32 nlink;
 522         int ret;
 523         int i;
 524         struct extent_buffer *eb;
 525         struct btrfs_inode_item *inode_item;
 526         struct scrub_warning *swarn = warn_ctx;
 527         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
 528         struct inode_fs_paths *ipath = NULL;
 529         struct btrfs_root *local_root;
 530         struct btrfs_key root_key;
 531         struct btrfs_key key;
 532
 533         root_key.objectid = root;
 534         root_key.type = BTRFS_ROOT_ITEM_KEY;
 535         root_key.offset = (u64)-1;
 536         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 537         if (IS_ERR(local_root)) {
 538                 ret = PTR_ERR(local_root);
 539                 goto err;
 540         }
 541
 542         /*
 543          * this makes the path point to (inum INODE_ITEM ioff)
 544          */
 545         key.objectid = inum;
 546         key.type = BTRFS_INODE_ITEM_KEY;
 547         key.offset = 0;
 548
 549         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 550         if (ret) {
 551                 btrfs_release_path(swarn->path);
 552                 goto err;
 553         }
 554
 555         eb = swarn->path->nodes[0];
 556         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 557                                         struct btrfs_inode_item);
 558         isize = btrfs_inode_size(eb, inode_item);
 559         nlink = btrfs_inode_nlink(eb, inode_item);
 560         btrfs_release_path(swarn->path);
 561
 562         ipath = init_ipath(4096, local_root, swarn->path);
 563         if (IS_ERR(ipath)) {
 564                 ret = PTR_ERR(ipath);
 565                 ipath = NULL;
 566                 goto err;
 567         }
 568         ret = paths_from_inode(inum, ipath);
 569
 570         if (ret < 0)
 571                 goto err;
 572
 573         /*
 574          * we deliberately ignore the bit ipath might have been too small to
 575          * hold all of the paths here
 576          */
 577         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 578                 btrfs_warn_in_rcu(fs_info, "%s at logical %llu on dev "
 579                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
 580                         "length %llu, links %u (path: %s)", swarn->errstr,
 581                         swarn->logical, rcu_str_deref(swarn->dev->name),
 582                         (unsigned long long)swarn->sector, root, inum, offset,
 583                         min(isize - offset, (u64)PAGE_SIZE), nlink,
 584                         (char *)(unsigned long)ipath->fspath->val[i]);
 585
 586         free_ipath(ipath);
 587         return 0;
 588
 589 err:
 590         btrfs_warn_in_rcu(fs_info, "%s at logical %llu on dev "
 591                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
 592                 "resolving failed with ret=%d", swarn->errstr,
 593                 swarn->logical, rcu_str_deref(swarn->dev->name),
 594                 (unsigned long long)swarn->sector, root, inum, offset, ret);
 595
 596         free_ipath(ipath);
 597         return 0;
 598 }
 599
 600 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 601 {
 602         struct btrfs_device *dev;
 603         struct btrfs_fs_info *fs_info;
 604         struct btrfs_path *path;
 605         struct btrfs_key found_key;
 606         struct extent_buffer *eb;
 607         struct btrfs_extent_item *ei;
 608         struct scrub_warning swarn;
 609         unsigned long ptr = 0;
 610         u64 extent_item_pos;
 611         u64 flags = 0;
 612         u64 ref_root;
 613         u32 item_size;
 614         u8 ref_level = 0;
 615         int ret;
 616
 617         WARN_ON(sblock->page_count < 1);
 618         dev = sblock->pagev[0]->dev;
 619         fs_info = sblock->sctx->dev_root->fs_info;
 620
 621         path = btrfs_alloc_path();
 622         if (!path)
 623                 return;
 624
 625         swarn.sector = (sblock->pagev[0]->physical) >> 9;
 626         swarn.logical = sblock->pagev[0]->logical;
 627         swarn.errstr = errstr;
 628         swarn.dev = NULL;
 629
 630         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 631                                   &flags);
 632         if (ret < 0)
 633                 goto out;
 634
 635         extent_item_pos = swarn.logical - found_key.objectid;
 636         swarn.extent_item_size = found_key.offset;
 637
 638         eb = path->nodes[0];
 639         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 640         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 641
 642         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 643                 do {
 644                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 645                                                       item_size, &ref_root,
 646                                                       &ref_level);
 647                         btrfs_warn_in_rcu(fs_info,
 648                                 "%s at logical %llu on dev %s, "
 649                                 "sector %llu: metadata %s (level %d) in tree "
 650                                 "%llu", errstr, swarn.logical,
 651                                 rcu_str_deref(dev->name),
 652                                 (unsigned long long)swarn.sector,
 653                                 ref_level ? "node" : "leaf",
 654                                 ret < 0 ? -1 : ref_level,
 655                                 ret < 0 ? -1 : ref_root);
 656                 } while (ret != 1);
 657                 btrfs_release_path(path);
 658         } else {
 659                 btrfs_release_path(path);
 660                 swarn.path = path;
 661                 swarn.dev = dev;
 662                 iterate_extent_inodes(fs_info, found_key.objectid,
 663                                         extent_item_pos, 1,
 664                                         scrub_print_warning_inode, &swarn);
 665         }
 666
 667 out:
 668         btrfs_free_path(path);
 669 }
 670
 671 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
 672 {
 673         struct page *page = NULL;
 674         unsigned long index;
 675         struct scrub_fixup_nodatasum *fixup = fixup_ctx;
 676         int ret;
 677         int corrected = 0;
 678         struct btrfs_key key;
 679         struct inode *inode = NULL;
 680         struct btrfs_fs_info *fs_info;
 681         u64 end = offset + PAGE_SIZE - 1;
 682         struct btrfs_root *local_root;
 683         int srcu_index;
 684
 685         key.objectid = root;
 686         key.type = BTRFS_ROOT_ITEM_KEY;
 687         key.offset = (u64)-1;
 688
 689         fs_info = fixup->root->fs_info;
 690         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
 691
 692         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
 693         if (IS_ERR(local_root)) {
 694                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 695                 return PTR_ERR(local_root);
 696         }
 697
 698         key.type = BTRFS_INODE_ITEM_KEY;
 699         key.objectid = inum;
 700         key.offset = 0;
 701         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
 702         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
 703         if (IS_ERR(inode))
 704                 return PTR_ERR(inode);
 705
 706         index = offset >> PAGE_SHIFT;
 707
 708         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 709         if (!page) {
 710                 ret = -ENOMEM;
 711                 goto out;
 712         }
 713
 714         if (PageUptodate(page)) {
 715                 if (PageDirty(page)) {
 716                         /*
 717                          * we need to write the data to the defect sector. the
 718                          * data that was in that sector is not in memory,
 719                          * because the page was modified. we must not write the
 720                          * modified page to that sector.
 721                          *
 722                          * TODO: what could be done here: wait for the delalloc
 723                          *       runner to write out that page (might involve
 724                          *       COW) and see whether the sector is still
 725                          *       referenced afterwards.
 726                          *
 727                          * For the meantime, we'll treat this error
 728                          * incorrectable, although there is a chance that a
 729                          * later scrub will find the bad sector again and that
 730                          * there's no dirty page in memory, then.
 731                          */
 732                         ret = -EIO;
 733                         goto out;
 734                 }
 735                 ret = repair_io_failure(inode, offset, PAGE_SIZE,
 736                                         fixup->logical, page,
 737                                         offset - page_offset(page),
 738                                         fixup->mirror_num);
 739                 unlock_page(page);
 740                 corrected = !ret;
 741         } else {
 742                 /*
 743                  * we need to get good data first. the general readpage path
 744                  * will call repair_io_failure for us, we just have to make
 745                  * sure we read the bad mirror.
 746                  */
 747                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 748                                         EXTENT_DAMAGED);
 749                 if (ret) {
 750                         /* set_extent_bits should give proper error */
 751                         WARN_ON(ret > 0);
 752                         if (ret > 0)
 753                                 ret = -EFAULT;
 754                         goto out;
 755                 }
 756
 757                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
 758                                                 btrfs_get_extent,
 759                                                 fixup->mirror_num);
 760                 wait_on_page_locked(page);
 761
 762                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
 763                                                 end, EXTENT_DAMAGED, 0, NULL);
 764                 if (!corrected)
 765                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
 766                                                 EXTENT_DAMAGED);
 767         }
 768
 769 out:
 770         if (page)
 771                 put_page(page);
 772
 773         iput(inode);
 774
 775         if (ret < 0)
 776                 return ret;
 777
 778         if (ret == 0 && corrected) {
 779                 /*
 780                  * we only need to call readpage for one of the inodes belonging
 781                  * to this extent. so make iterate_extent_inodes stop
 782                  */
 783                 return 1;
 784         }
 785
 786         return -EIO;
 787 }
 788
 789 static void scrub_fixup_nodatasum(struct btrfs_work *work)
 790 {
 791         int ret;
 792         struct scrub_fixup_nodatasum *fixup;
 793         struct scrub_ctx *sctx;
 794         struct btrfs_trans_handle *trans = NULL;
 795         struct btrfs_path *path;
 796         int uncorrectable = 0;
 797
 798         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
 799         sctx = fixup->sctx;
 800
 801         path = btrfs_alloc_path();
 802         if (!path) {
 803                 spin_lock(&sctx->stat_lock);
 804                 ++sctx->stat.malloc_errors;
 805                 spin_unlock(&sctx->stat_lock);
 806                 uncorrectable = 1;
 807                 goto out;
 808         }
 809
 810         trans = btrfs_join_transaction(fixup->root);
 811         if (IS_ERR(trans)) {
 812                 uncorrectable = 1;
 813                 goto out;
 814         }
 815
 816         /*
 817          * the idea is to trigger a regular read through the standard path. we
 818          * read a page from the (failed) logical address by specifying the
 819          * corresponding copynum of the failed sector. thus, that readpage is
 820          * expected to fail.
 821          * that is the point where on-the-fly error correction will kick in
 822          * (once it's finished) and rewrite the failed sector if a good copy
 823          * can be found.
 824          */
 825         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
 826                                                 path, scrub_fixup_readpage,
 827                                                 fixup);
 828         if (ret < 0) {
 829                 uncorrectable = 1;
 830                 goto out;
 831         }
 832         WARN_ON(ret != 1);
 833
 834         spin_lock(&sctx->stat_lock);
 835         ++sctx->stat.corrected_errors;
 836         spin_unlock(&sctx->stat_lock);
 837
 838 out:
 839         if (trans && !IS_ERR(trans))
 840                 btrfs_end_transaction(trans, fixup->root);
 841         if (uncorrectable) {
 842                 spin_lock(&sctx->stat_lock);
 843                 ++sctx->stat.uncorrectable_errors;
 844                 spin_unlock(&sctx->stat_lock);
 845                 btrfs_dev_replace_stats_inc(
 846                         &sctx->dev_root->fs_info->dev_replace.
 847                         num_uncorrectable_read_errors);
 848                 btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
 849                     "unable to fixup (nodatasum) error at logical %llu on dev %s",
 850                         fixup->logical, rcu_str_deref(fixup->dev->name));
 851         }
 852
 853         btrfs_free_path(path);
 854         kfree(fixup);
 855
 856         scrub_pending_trans_workers_dec(sctx);
 857 }
 858
 859 static inline void scrub_get_recover(struct scrub_recover *recover)
 860 {
 861         atomic_inc(&recover->refs);
 862 }
 863
 864 static inline void scrub_put_recover(struct scrub_recover *recover)
 865 {
 866         if (atomic_dec_and_test(&recover->refs)) {
 867                 btrfs_put_bbio(recover->bbio);
 868                 kfree(recover);
 869         }
 870 }
 871
 872 /*
 873  * scrub_handle_errored_block gets called when either verification of the
 874  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 875  * case, this function handles all pages in the bio, even though only one
 876  * may be bad.
 877  * The goal of this function is to repair the errored block by using the
 878  * contents of one of the mirrors.
 879  */
 880 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 881 {
 882         struct scrub_ctx *sctx = sblock_to_check->sctx;
 883         struct btrfs_device *dev;
 884         struct btrfs_fs_info *fs_info;
 885         u64 length;
 886         u64 logical;
 887         unsigned int failed_mirror_index;
 888         unsigned int is_metadata;
 889         unsigned int have_csum;
 890         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 891         struct scrub_block *sblock_bad;
 892         int ret;
 893         int mirror_index;
 894         int page_num;
 895         int success;
 896         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 897                                       DEFAULT_RATELIMIT_BURST);
 898
 899         BUG_ON(sblock_to_check->page_count < 1);
 900         fs_info = sctx->dev_root->fs_info;
 901         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 902                 /*
 903                  * if we find an error in a super block, we just report it.
 904                  * They will get written with the next transaction commit
 905                  * anyway
 906                  */
 907                 spin_lock(&sctx->stat_lock);
 908                 ++sctx->stat.super_errors;
 909                 spin_unlock(&sctx->stat_lock);
 910                 return 0;
 911         }
 912         length = sblock_to_check->page_count * PAGE_SIZE;
 913         logical = sblock_to_check->pagev[0]->logical;
 914         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 915         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 916         is_metadata = !(sblock_to_check->pagev[0]->flags &
 917                         BTRFS_EXTENT_FLAG_DATA);
 918         have_csum = sblock_to_check->pagev[0]->have_csum;
 919         dev = sblock_to_check->pagev[0]->dev;
 920
 921         if (sctx->is_dev_replace && !is_metadata && !have_csum) {
 922                 sblocks_for_recheck = NULL;
 923                 goto nodatasum_case;
 924         }
 925
 926         /*
 927          * read all mirrors one after the other. This includes to
 928          * re-read the extent or metadata block that failed (that was
 929          * the cause that this fixup code is called) another time,
 930          * page by page this time in order to know which pages
 931          * caused I/O errors and which ones are good (for all mirrors).
 932          * It is the goal to handle the situation when more than one
 933          * mirror contains I/O errors, but the errors do not
 934          * overlap, i.e. the data can be repaired by selecting the
 935          * pages from those mirrors without I/O error on the
 936          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 937          * would be that mirror #1 has an I/O error on the first page,
 938          * the second page is good, and mirror #2 has an I/O error on
 939          * the second page, but the first page is good.
 940          * Then the first page of the first mirror can be repaired by
 941          * taking the first page of the second mirror, and the
 942          * second page of the second mirror can be repaired by
 943          * copying the contents of the 2nd page of the 1st mirror.
 944          * One more note: if the pages of one mirror contain I/O
 945          * errors, the checksum cannot be verified. In order to get
 946          * the best data for repairing, the first attempt is to find
 947          * a mirror without I/O errors and with a validated checksum.
 948          * Only if this is not possible, the pages are picked from
 949          * mirrors with I/O errors without considering the checksum.
 950          * If the latter is the case, at the end, the checksum of the
 951          * repaired area is verified in order to correctly maintain
 952          * the statistics.
 953          */
 954
 955         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
 956                                       sizeof(*sblocks_for_recheck), GFP_NOFS);
 957         if (!sblocks_for_recheck) {
 958                 spin_lock(&sctx->stat_lock);
 959                 sctx->stat.malloc_errors++;
 960                 sctx->stat.read_errors++;
 961                 sctx->stat.uncorrectable_errors++;
 962                 spin_unlock(&sctx->stat_lock);
 963                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 964                 goto out;
 965         }
 966
 967         /* setup the context, map the logical blocks and alloc the pages */
 968         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
 969         if (ret) {
 970                 spin_lock(&sctx->stat_lock);
 971                 sctx->stat.read_errors++;
 972                 sctx->stat.uncorrectable_errors++;
 973                 spin_unlock(&sctx->stat_lock);
 974                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 975                 goto out;
 976         }
 977         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 978         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 979
 980         /* build and submit the bios for the failed mirror, check checksums */
 981         scrub_recheck_block(fs_info, sblock_bad, 1);
 982
 983         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 984             sblock_bad->no_io_error_seen) {
 985                 /*
 986                  * the error disappeared after reading page by page, or
 987                  * the area was part of a huge bio and other parts of the
 988                  * bio caused I/O errors, or the block layer merged several
 989                  * read requests into one and the error is caused by a
 990                  * different bio (usually one of the two latter cases is
 991                  * the cause)
 992                  */
 993                 spin_lock(&sctx->stat_lock);
 994                 sctx->stat.unverified_errors++;
 995                 sblock_to_check->data_corrected = 1;
 996                 spin_unlock(&sctx->stat_lock);
 997
 998                 if (sctx->is_dev_replace)
 999                         scrub_write_block_to_dev_replace(sblock_bad);
1000                 goto out;
1001         }
1002
1003         if (!sblock_bad->no_io_error_seen) {
1004                 spin_lock(&sctx->stat_lock);
1005                 sctx->stat.read_errors++;
1006                 spin_unlock(&sctx->stat_lock);
1007                 if (__ratelimit(&_rs))
1008                         scrub_print_warning("i/o error", sblock_to_check);
1009                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
1010         } else if (sblock_bad->checksum_error) {
1011                 spin_lock(&sctx->stat_lock);
1012                 sctx->stat.csum_errors++;
1013                 spin_unlock(&sctx->stat_lock);
1014                 if (__ratelimit(&_rs))
1015                         scrub_print_warning("checksum error", sblock_to_check);
1016                 btrfs_dev_stat_inc_and_print(dev,
1017                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
1018         } else if (sblock_bad->header_error) {
1019                 spin_lock(&sctx->stat_lock);
1020                 sctx->stat.verify_errors++;
1021                 spin_unlock(&sctx->stat_lock);
1022                 if (__ratelimit(&_rs))
1023                         scrub_print_warning("checksum/header error",
1024                                             sblock_to_check);
1025                 if (sblock_bad->generation_error)
1026                         btrfs_dev_stat_inc_and_print(dev,
1027                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1028                 else
1029                         btrfs_dev_stat_inc_and_print(dev,
1030                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1031         }
1032
1033         if (sctx->readonly) {
1034                 ASSERT(!sctx->is_dev_replace);
1035                 goto out;
1036         }
1037
1038         if (!is_metadata && !have_csum) {
1039                 struct scrub_fixup_nodatasum *fixup_nodatasum;
1040
1041                 WARN_ON(sctx->is_dev_replace);
1042
1043 nodatasum_case:
1044
1045                 /*
1046                  * !is_metadata and !have_csum, this means that the data
1047                  * might not be COWed, that it might be modified
1048                  * concurrently. The general strategy to work on the
1049                  * commit root does not help in the case when COW is not
1050                  * used.
1051                  */
1052                 fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum), GFP_NOFS);
1053                 if (!fixup_nodatasum)
1054                         goto did_not_correct_error;
1055                 fixup_nodatasum->sctx = sctx;
1056                 fixup_nodatasum->dev = dev;
1057                 fixup_nodatasum->logical = logical;
1058                 fixup_nodatasum->root = fs_info->extent_root;
1059                 fixup_nodatasum->mirror_num = failed_mirror_index + 1;
1060                 scrub_pending_trans_workers_inc(sctx);
1061                 btrfs_init_work(&fixup_nodatasum->work, btrfs_scrub_helper,
1062                                 scrub_fixup_nodatasum, NULL, NULL);
1063                 btrfs_queue_work(fs_info->scrub_workers,
1064                                  &fixup_nodatasum->work);
1065                 goto out;
1066         }
1067
1068         /*
1069          * now build and submit the bios for the other mirrors, check
1070          * checksums.
1071          * First try to pick the mirror which is completely without I/O
1072          * errors and also does not have a checksum error.
1073          * If one is found, and if a checksum is present, the full block
1074          * that is known to contain an error is rewritten. Afterwards
1075          * the block is known to be corrected.
1076          * If a mirror is found which is completely correct, and no
1077          * checksum is present, only those pages are rewritten that had
1078          * an I/O error in the block to be repaired, since it cannot be
1079          * determined, which copy of the other pages is better (and it
1080          * could happen otherwise that a correct page would be
1081          * overwritten by a bad one).
1082          */
1083         for (mirror_index = 0;
1084              mirror_index < BTRFS_MAX_MIRRORS &&
1085              sblocks_for_recheck[mirror_index].page_count > 0;
1086              mirror_index++) {
1087                 struct scrub_block *sblock_other;
1088
1089                 if (mirror_index == failed_mirror_index)
1090                         continue;
1091                 sblock_other = sblocks_for_recheck + mirror_index;
1092
1093                 /* build and submit the bios, check checksums */
1094                 scrub_recheck_block(fs_info, sblock_other, 0);
1095
1096                 if (!sblock_other->header_error &&
1097                     !sblock_other->checksum_error &&
1098                     sblock_other->no_io_error_seen) {
1099                         if (sctx->is_dev_replace) {
1100                                 scrub_write_block_to_dev_replace(sblock_other);
1101                                 goto corrected_error;
1102                         } else {
1103                                 ret = scrub_repair_block_from_good_copy(
1104                                                 sblock_bad, sblock_other);
1105                                 if (!ret)
1106                                         goto corrected_error;
1107                         }
1108                 }
1109         }
1110
1111         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1112                 goto did_not_correct_error;
1113
1114         /*
1115          * In case of I/O errors in the area that is supposed to be
1116          * repaired, continue by picking good copies of those pages.
1117          * Select the good pages from mirrors to rewrite bad pages from
1118          * the area to fix. Afterwards verify the checksum of the block
1119          * that is supposed to be repaired. This verification step is
1120          * only done for the purpose of statistic counting and for the
1121          * final scrub report, whether errors remain.
1122          * A perfect algorithm could make use of the checksum and try
1123          * all possible combinations of pages from the different mirrors
1124          * until the checksum verification succeeds. For example, when
1125          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1126          * of mirror #2 is readable but the final checksum test fails,
1127          * then the 2nd page of mirror #3 could be tried, whether now
1128          * the final checksum succeeds. But this would be a rare
1129          * exception and is therefore not implemented. At least it is
1130          * avoided that the good copy is overwritten.
1131          * A more useful improvement would be to pick the sectors
1132          * without I/O error based on sector sizes (512 bytes on legacy
1133          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1134          * mirror could be repaired by taking 512 byte of a different
1135          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1136          * area are unreadable.
1137          */
1138         success = 1;
1139         for (page_num = 0; page_num < sblock_bad->page_count;
1140              page_num++) {
1141                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1142                 struct scrub_block *sblock_other = NULL;
1143
1144                 /* skip no-io-error page in scrub */
1145                 if (!page_bad->io_error && !sctx->is_dev_replace)
1146                         continue;
1147
1148                 /* try to find no-io-error page in mirrors */
1149                 if (page_bad->io_error) {
1150                         for (mirror_index = 0;
1151                              mirror_index < BTRFS_MAX_MIRRORS &&
1152                              sblocks_for_recheck[mirror_index].page_count > 0;
1153                              mirror_index++) {
1154                                 if (!sblocks_for_recheck[mirror_index].
1155                                     pagev[page_num]->io_error) {
1156                                         sblock_other = sblocks_for_recheck +
1157                                                        mirror_index;
1158                                         break;
1159                                 }
1160                         }
1161                         if (!sblock_other)
1162                                 success = 0;
1163                 }
1164
1165                 if (sctx->is_dev_replace) {
1166                         /*
1167                          * did not find a mirror to fetch the page
1168                          * from. scrub_write_page_to_dev_replace()
1169                          * handles this case (page->io_error), by
1170                          * filling the block with zeros before
1171                          * submitting the write request
1172                          */
1173                         if (!sblock_other)
1174                                 sblock_other = sblock_bad;
1175
1176                         if (scrub_write_page_to_dev_replace(sblock_other,
1177                                                             page_num) != 0) {
1178                                 btrfs_dev_replace_stats_inc(
1179                                         &sctx->dev_root->
1180                                         fs_info->dev_replace.
1181                                         num_write_errors);
1182                                 success = 0;
1183                         }
1184                 } else if (sblock_other) {
1185                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1186                                                                sblock_other,
1187                                                                page_num, 0);
1188                         if (0 == ret)
1189                                 page_bad->io_error = 0;
1190                         else
1191                                 success = 0;
1192                 }
1193         }
1194
1195         if (success && !sctx->is_dev_replace) {
1196                 if (is_metadata || have_csum) {
1197                         /*
1198                          * need to verify the checksum now that all
1199                          * sectors on disk are repaired (the write
1200                          * request for data to be repaired is on its way).
1201                          * Just be lazy and use scrub_recheck_block()
1202                          * which re-reads the data before the checksum
1203                          * is verified, but most likely the data comes out
1204                          * of the page cache.
1205                          */
1206                         scrub_recheck_block(fs_info, sblock_bad, 1);
1207                         if (!sblock_bad->header_error &&
1208                             !sblock_bad->checksum_error &&
1209                             sblock_bad->no_io_error_seen)
1210                                 goto corrected_error;
1211                         else
1212                                 goto did_not_correct_error;
1213                 } else {
1214 corrected_error:
1215                         spin_lock(&sctx->stat_lock);
1216                         sctx->stat.corrected_errors++;
1217                         sblock_to_check->data_corrected = 1;
1218                         spin_unlock(&sctx->stat_lock);
1219                         btrfs_err_rl_in_rcu(fs_info,
1220                                 "fixed up error at logical %llu on dev %s",
1221                                 logical, rcu_str_deref(dev->name));
1222                 }
1223         } else {
1224 did_not_correct_error:
1225                 spin_lock(&sctx->stat_lock);
1226                 sctx->stat.uncorrectable_errors++;
1227                 spin_unlock(&sctx->stat_lock);
1228                 btrfs_err_rl_in_rcu(fs_info,
1229                         "unable to fixup (regular) error at logical %llu on dev %s",
1230                         logical, rcu_str_deref(dev->name));
1231         }
1232
1233 out:
1234         if (sblocks_for_recheck) {
1235                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1236                      mirror_index++) {
1237                         struct scrub_block *sblock = sblocks_for_recheck +
1238                                                      mirror_index;
1239                         struct scrub_recover *recover;
1240                         int page_index;
1241
1242                         for (page_index = 0; page_index < sblock->page_count;
1243                              page_index++) {
1244                                 sblock->pagev[page_index]->sblock = NULL;
1245                                 recover = sblock->pagev[page_index]->recover;
1246                                 if (recover) {
1247                                         scrub_put_recover(recover);
1248                                         sblock->pagev[page_index]->recover =
1249                                                                         NULL;
1250                                 }
1251                                 scrub_page_put(sblock->pagev[page_index]);
1252                         }
1253                 }
1254                 kfree(sblocks_for_recheck);
1255         }
1256
1257         return 0;
1258 }
1259
1260 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1261 {
1262         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1263                 return 2;
1264         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1265                 return 3;
1266         else
1267                 return (int)bbio->num_stripes;
1268 }
1269
1270 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1271                                                  u64 *raid_map,
1272                                                  u64 mapped_length,
1273                                                  int nstripes, int mirror,
1274                                                  int *stripe_index,
1275                                                  u64 *stripe_offset)
1276 {
1277         int i;
1278
1279         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1280                 /* RAID5/6 */
1281                 for (i = 0; i < nstripes; i++) {
1282                         if (raid_map[i] == RAID6_Q_STRIPE ||
1283                             raid_map[i] == RAID5_P_STRIPE)
1284                                 continue;
1285
1286                         if (logical >= raid_map[i] &&
1287                             logical < raid_map[i] + mapped_length)
1288                                 break;
1289                 }
1290
1291                 *stripe_index = i;
1292                 *stripe_offset = logical - raid_map[i];
1293         } else {
1294                 /* The other RAID type */
1295                 *stripe_index = mirror;
1296                 *stripe_offset = 0;
1297         }
1298 }
1299
1300 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1301                                      struct scrub_block *sblocks_for_recheck)
1302 {
1303         struct scrub_ctx *sctx = original_sblock->sctx;
1304         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
1305         u64 length = original_sblock->page_count * PAGE_SIZE;
1306         u64 logical = original_sblock->pagev[0]->logical;
1307         u64 generation = original_sblock->pagev[0]->generation;
1308         u64 flags = original_sblock->pagev[0]->flags;
1309         u64 have_csum = original_sblock->pagev[0]->have_csum;
1310         struct scrub_recover *recover;
1311         struct btrfs_bio *bbio;
1312         u64 sublen;
1313         u64 mapped_length;
1314         u64 stripe_offset;
1315         int stripe_index;
1316         int page_index = 0;
1317         int mirror_index;
1318         int nmirrors;
1319         int ret;
1320
1321         /*
1322          * note: the two members refs and outstanding_pages
1323          * are not used (and not set) in the blocks that are used for
1324          * the recheck procedure
1325          */
1326
1327         while (length > 0) {
1328                 sublen = min_t(u64, length, PAGE_SIZE);
1329                 mapped_length = sublen;
1330                 bbio = NULL;
1331
1332                 /*
1333                  * with a length of PAGE_SIZE, each returned stripe
1334                  * represents one mirror
1335                  */
1336                 ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical,
1337                                        &mapped_length, &bbio, 0, 1);
1338                 if (ret || !bbio || mapped_length < sublen) {
1339                         btrfs_put_bbio(bbio);
1340                         return -EIO;
1341                 }
1342
1343                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1344                 if (!recover) {
1345                         btrfs_put_bbio(bbio);
1346                         return -ENOMEM;
1347                 }
1348
1349                 atomic_set(&recover->refs, 1);
1350                 recover->bbio = bbio;
1351                 recover->map_length = mapped_length;
1352
1353                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1354
1355                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1356
1357                 for (mirror_index = 0; mirror_index < nmirrors;
1358                      mirror_index++) {
1359                         struct scrub_block *sblock;
1360                         struct scrub_page *page;
1361
1362                         sblock = sblocks_for_recheck + mirror_index;
1363                         sblock->sctx = sctx;
1364
1365                         page = kzalloc(sizeof(*page), GFP_NOFS);
1366                         if (!page) {
1367 leave_nomem:
1368                                 spin_lock(&sctx->stat_lock);
1369                                 sctx->stat.malloc_errors++;
1370                                 spin_unlock(&sctx->stat_lock);
1371                                 scrub_put_recover(recover);
1372                                 return -ENOMEM;
1373                         }
1374                         scrub_page_get(page);
1375                         sblock->pagev[page_index] = page;
1376                         page->sblock = sblock;
1377                         page->flags = flags;
1378                         page->generation = generation;
1379                         page->logical = logical;
1380                         page->have_csum = have_csum;
1381                         if (have_csum)
1382                                 memcpy(page->csum,
1383                                        original_sblock->pagev[0]->csum,
1384                                        sctx->csum_size);
1385
1386                         scrub_stripe_index_and_offset(logical,
1387                                                       bbio->map_type,
1388                                                       bbio->raid_map,
1389                                                       mapped_length,
1390                                                       bbio->num_stripes -
1391                                                       bbio->num_tgtdevs,
1392                                                       mirror_index,
1393                                                       &stripe_index,
1394                                                       &stripe_offset);
1395                         page->physical = bbio->stripes[stripe_index].physical +
1396                                          stripe_offset;
1397                         page->dev = bbio->stripes[stripe_index].dev;
1398
1399                         BUG_ON(page_index >= original_sblock->page_count);
1400                         page->physical_for_dev_replace =
1401                                 original_sblock->pagev[page_index]->
1402                                 physical_for_dev_replace;
1403                         /* for missing devices, dev->bdev is NULL */
1404                         page->mirror_num = mirror_index + 1;
1405                         sblock->page_count++;
1406                         page->page = alloc_page(GFP_NOFS);
1407                         if (!page->page)
1408                                 goto leave_nomem;
1409
1410                         scrub_get_recover(recover);
1411                         page->recover = recover;
1412                 }
1413                 scrub_put_recover(recover);
1414                 length -= sublen;
1415                 logical += sublen;
1416                 page_index++;
1417         }
1418
1419         return 0;
1420 }
1421
1422 struct scrub_bio_ret {
1423         struct completion event;
1424         int error;
1425 };
1426
1427 static void scrub_bio_wait_endio(struct bio *bio)
1428 {
1429         struct scrub_bio_ret *ret = bio->bi_private;
1430
1431         ret->error = bio->bi_error;
1432         complete(&ret->event);
1433 }
1434
1435 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
1436 {
1437         return page->recover &&
1438                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
1439 }
1440
1441 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1442                                         struct bio *bio,
1443                                         struct scrub_page *page)
1444 {
1445         struct scrub_bio_ret done;
1446         int ret;
1447
1448         init_completion(&done.event);
1449         done.error = 0;
1450         bio->bi_iter.bi_sector = page->logical >> 9;
1451         bio->bi_private = &done;
1452         bio->bi_end_io = scrub_bio_wait_endio;
1453
1454         ret = raid56_parity_recover(fs_info->fs_root, bio, page->recover->bbio,
1455                                     page->recover->map_length,
1456                                     page->mirror_num, 0);
1457         if (ret)
1458                 return ret;
1459
1460         wait_for_completion(&done.event);
1461         if (done.error)
1462                 return -EIO;
1463
1464         return 0;
1465 }
1466
1467 /*
1468  * this function will check the on disk data for checksum errors, header
1469  * errors and read I/O errors. If any I/O errors happen, the exact pages
1470  * which are errored are marked as being bad. The goal is to enable scrub
1471  * to take those pages that are not errored from all the mirrors so that
1472  * the pages that are errored in the just handled mirror can be repaired.
1473  */
1474 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1475                                 struct scrub_block *sblock,
1476                                 int retry_failed_mirror)
1477 {
1478         int page_num;
1479
1480         sblock->no_io_error_seen = 1;
1481
1482         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1483                 struct bio *bio;
1484                 struct scrub_page *page = sblock->pagev[page_num];
1485
1486                 if (page->dev->bdev == NULL) {
1487                         page->io_error = 1;
1488                         sblock->no_io_error_seen = 0;
1489                         continue;
1490                 }
1491
1492                 WARN_ON(!page->page);
1493                 bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1494                 if (!bio) {
1495                         page->io_error = 1;
1496                         sblock->no_io_error_seen = 0;
1497                         continue;
1498                 }
1499                 bio->bi_bdev = page->dev->bdev;
1500
1501                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1502                 if (!retry_failed_mirror && scrub_is_page_on_raid56(page)) {
1503                         if (scrub_submit_raid56_bio_wait(fs_info, bio, page))
1504                                 sblock->no_io_error_seen = 0;
1505                 } else {
1506                         bio->bi_iter.bi_sector = page->physical >> 9;
1507
1508                         if (btrfsic_submit_bio_wait(READ, bio))
1509                                 sblock->no_io_error_seen = 0;
1510                 }
1511
1512                 bio_put(bio);
1513         }
1514
1515         if (sblock->no_io_error_seen)
1516                 scrub_recheck_block_checksum(sblock);
1517 }
1518
1519 static inline int scrub_check_fsid(u8 fsid[],
1520                                    struct scrub_page *spage)
1521 {
1522         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1523         int ret;
1524
1525         ret = memcmp(fsid, fs_devices->fsid, BTRFS_UUID_SIZE);
1526         return !ret;
1527 }
1528
1529 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1530 {
1531         sblock->header_error = 0;
1532         sblock->checksum_error = 0;
1533         sblock->generation_error = 0;
1534
1535         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1536                 scrub_checksum_data(sblock);
1537         else
1538                 scrub_checksum_tree_block(sblock);
1539 }
1540
1541 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1542                                              struct scrub_block *sblock_good)
1543 {
1544         int page_num;
1545         int ret = 0;
1546
1547         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1548                 int ret_sub;
1549
1550                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1551                                                            sblock_good,
1552                                                            page_num, 1);
1553                 if (ret_sub)
1554                         ret = ret_sub;
1555         }
1556
1557         return ret;
1558 }
1559
1560 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1561                                             struct scrub_block *sblock_good,
1562                                             int page_num, int force_write)
1563 {
1564         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1565         struct scrub_page *page_good = sblock_good->pagev[page_num];
1566
1567         BUG_ON(page_bad->page == NULL);
1568         BUG_ON(page_good->page == NULL);
1569         if (force_write || sblock_bad->header_error ||
1570             sblock_bad->checksum_error || page_bad->io_error) {
1571                 struct bio *bio;
1572                 int ret;
1573
1574                 if (!page_bad->dev->bdev) {
1575                         btrfs_warn_rl(sblock_bad->sctx->dev_root->fs_info,
1576                                 "scrub_repair_page_from_good_copy(bdev == NULL) "
1577                                 "is unexpected");
1578                         return -EIO;
1579                 }
1580
1581                 bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
1582                 if (!bio)
1583                         return -EIO;
1584                 bio->bi_bdev = page_bad->dev->bdev;
1585                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1586
1587                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1588                 if (PAGE_SIZE != ret) {
1589                         bio_put(bio);
1590                         return -EIO;
1591                 }
1592
1593                 if (btrfsic_submit_bio_wait(WRITE, bio)) {
1594                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1595                                 BTRFS_DEV_STAT_WRITE_ERRS);
1596                         btrfs_dev_replace_stats_inc(
1597                                 &sblock_bad->sctx->dev_root->fs_info->
1598                                 dev_replace.num_write_errors);
1599                         bio_put(bio);
1600                         return -EIO;
1601                 }
1602                 bio_put(bio);
1603         }
1604
1605         return 0;
1606 }
1607
1608 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1609 {
1610         int page_num;
1611
1612         /*
1613          * This block is used for the check of the parity on the source device,
1614          * so the data needn't be written into the destination device.
1615          */
1616         if (sblock->sparity)
1617                 return;
1618
1619         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1620                 int ret;
1621
1622                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1623                 if (ret)
1624                         btrfs_dev_replace_stats_inc(
1625                                 &sblock->sctx->dev_root->fs_info->dev_replace.
1626                                 num_write_errors);
1627         }
1628 }
1629
1630 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1631                                            int page_num)
1632 {
1633         struct scrub_page *spage = sblock->pagev[page_num];
1634
1635         BUG_ON(spage->page == NULL);
1636         if (spage->io_error) {
1637                 void *mapped_buffer = kmap_atomic(spage->page);
1638
1639                 memset(mapped_buffer, 0, PAGE_SIZE);
1640                 flush_dcache_page(spage->page);
1641                 kunmap_atomic(mapped_buffer);
1642         }
1643         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1644 }
1645
1646 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1647                                     struct scrub_page *spage)
1648 {
1649         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1650         struct scrub_bio *sbio;
1651         int ret;
1652
1653         mutex_lock(&wr_ctx->wr_lock);
1654 again:
1655         if (!wr_ctx->wr_curr_bio) {
1656                 wr_ctx->wr_curr_bio = kzalloc(sizeof(*wr_ctx->wr_curr_bio),
1657                                               GFP_KERNEL);
1658                 if (!wr_ctx->wr_curr_bio) {
1659                         mutex_unlock(&wr_ctx->wr_lock);
1660                         return -ENOMEM;
1661                 }
1662                 wr_ctx->wr_curr_bio->sctx = sctx;
1663                 wr_ctx->wr_curr_bio->page_count = 0;
1664         }
1665         sbio = wr_ctx->wr_curr_bio;
1666         if (sbio->page_count == 0) {
1667                 struct bio *bio;
1668
1669                 sbio->physical = spage->physical_for_dev_replace;
1670                 sbio->logical = spage->logical;
1671                 sbio->dev = wr_ctx->tgtdev;
1672                 bio = sbio->bio;
1673                 if (!bio) {
1674                         bio = btrfs_io_bio_alloc(GFP_KERNEL,
1675                                         wr_ctx->pages_per_wr_bio);
1676                         if (!bio) {
1677                                 mutex_unlock(&wr_ctx->wr_lock);
1678                                 return -ENOMEM;
1679                         }
1680                         sbio->bio = bio;
1681                 }
1682
1683                 bio->bi_private = sbio;
1684                 bio->bi_end_io = scrub_wr_bio_end_io;
1685                 bio->bi_bdev = sbio->dev->bdev;
1686                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1687                 sbio->err = 0;
1688         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1689                    spage->physical_for_dev_replace ||
1690                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1691                    spage->logical) {
1692                 scrub_wr_submit(sctx);
1693                 goto again;
1694         }
1695
1696         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1697         if (ret != PAGE_SIZE) {
1698                 if (sbio->page_count < 1) {
1699                         bio_put(sbio->bio);
1700                         sbio->bio = NULL;
1701                         mutex_unlock(&wr_ctx->wr_lock);
1702                         return -EIO;
1703                 }
1704                 scrub_wr_submit(sctx);
1705                 goto again;
1706         }
1707
1708         sbio->pagev[sbio->page_count] = spage;
1709         scrub_page_get(spage);
1710         sbio->page_count++;
1711         if (sbio->page_count == wr_ctx->pages_per_wr_bio)
1712                 scrub_wr_submit(sctx);
1713         mutex_unlock(&wr_ctx->wr_lock);
1714
1715         return 0;
1716 }
1717
1718 static void scrub_wr_submit(struct scrub_ctx *sctx)
1719 {
1720         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1721         struct scrub_bio *sbio;
1722
1723         if (!wr_ctx->wr_curr_bio)
1724                 return;
1725
1726         sbio = wr_ctx->wr_curr_bio;
1727         wr_ctx->wr_curr_bio = NULL;
1728         WARN_ON(!sbio->bio->bi_bdev);
1729         scrub_pending_bio_inc(sctx);
1730         /* process all writes in a single worker thread. Then the block layer
1731          * orders the requests before sending them to the driver which
1732          * doubled the write performance on spinning disks when measured
1733          * with Linux 3.5 */
1734         btrfsic_submit_bio(WRITE, sbio->bio);
1735 }
1736
1737 static void scrub_wr_bio_end_io(struct bio *bio)
1738 {
1739         struct scrub_bio *sbio = bio->bi_private;
1740         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
1741
1742         sbio->err = bio->bi_error;
1743         sbio->bio = bio;
1744
1745         btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
1746                          scrub_wr_bio_end_io_worker, NULL, NULL);
1747         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1748 }
1749
1750 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1751 {
1752         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1753         struct scrub_ctx *sctx = sbio->sctx;
1754         int i;
1755
1756         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1757         if (sbio->err) {
1758                 struct btrfs_dev_replace *dev_replace =
1759                         &sbio->sctx->dev_root->fs_info->dev_replace;
1760
1761                 for (i = 0; i < sbio->page_count; i++) {
1762                         struct scrub_page *spage = sbio->pagev[i];
1763
1764                         spage->io_error = 1;
1765                         btrfs_dev_replace_stats_inc(&dev_replace->
1766                                                     num_write_errors);
1767                 }
1768         }
1769
1770         for (i = 0; i < sbio->page_count; i++)
1771                 scrub_page_put(sbio->pagev[i]);
1772
1773         bio_put(sbio->bio);
1774         kfree(sbio);
1775         scrub_pending_bio_dec(sctx);
1776 }
1777
1778 static int scrub_checksum(struct scrub_block *sblock)
1779 {
1780         u64 flags;
1781         int ret;
1782
1783         /*
1784          * No need to initialize these stats currently,
1785          * because this function only use return value
1786          * instead of these stats value.
1787          *
1788          * Todo:
1789          * always use stats
1790          */
1791         sblock->header_error = 0;
1792         sblock->generation_error = 0;
1793         sblock->checksum_error = 0;
1794
1795         WARN_ON(sblock->page_count < 1);
1796         flags = sblock->pagev[0]->flags;
1797         ret = 0;
1798         if (flags & BTRFS_EXTENT_FLAG_DATA)
1799                 ret = scrub_checksum_data(sblock);
1800         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1801                 ret = scrub_checksum_tree_block(sblock);
1802         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1803                 (void)scrub_checksum_super(sblock);
1804         else
1805                 WARN_ON(1);
1806         if (ret)
1807                 scrub_handle_errored_block(sblock);
1808
1809         return ret;
1810 }
1811
1812 static int scrub_checksum_data(struct scrub_block *sblock)
1813 {
1814         struct scrub_ctx *sctx = sblock->sctx;
1815         u8 csum[BTRFS_CSUM_SIZE];
1816         u8 *on_disk_csum;
1817         struct page *page;
1818         void *buffer;
1819         u32 crc = ~(u32)0;
1820         u64 len;
1821         int index;
1822
1823         BUG_ON(sblock->page_count < 1);
1824         if (!sblock->pagev[0]->have_csum)
1825                 return 0;
1826
1827         on_disk_csum = sblock->pagev[0]->csum;
1828         page = sblock->pagev[0]->page;
1829         buffer = kmap_atomic(page);
1830
1831         len = sctx->sectorsize;
1832         index = 0;
1833         for (;;) {
1834                 u64 l = min_t(u64, len, PAGE_SIZE);
1835
1836                 crc = btrfs_csum_data(buffer, crc, l);
1837                 kunmap_atomic(buffer);
1838                 len -= l;
1839                 if (len == 0)
1840                         break;
1841                 index++;
1842                 BUG_ON(index >= sblock->page_count);
1843                 BUG_ON(!sblock->pagev[index]->page);
1844                 page = sblock->pagev[index]->page;
1845                 buffer = kmap_atomic(page);
1846         }
1847
1848         btrfs_csum_final(crc, csum);
1849         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1850                 sblock->checksum_error = 1;
1851
1852         return sblock->checksum_error;
1853 }
1854
1855 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1856 {
1857         struct scrub_ctx *sctx = sblock->sctx;
1858         struct btrfs_header *h;
1859         struct btrfs_root *root = sctx->dev_root;
1860         struct btrfs_fs_info *fs_info = root->fs_info;
1861         u8 calculated_csum[BTRFS_CSUM_SIZE];
1862         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1863         struct page *page;
1864         void *mapped_buffer;
1865         u64 mapped_size;
1866         void *p;
1867         u32 crc = ~(u32)0;
1868         u64 len;
1869         int index;
1870
1871         BUG_ON(sblock->page_count < 1);
1872         page = sblock->pagev[0]->page;
1873         mapped_buffer = kmap_atomic(page);
1874         h = (struct btrfs_header *)mapped_buffer;
1875         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1876
1877         /*
1878          * we don't use the getter functions here, as we
1879          * a) don't have an extent buffer and
1880          * b) the page is already kmapped
1881          */
1882         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1883                 sblock->header_error = 1;
1884
1885         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
1886                 sblock->header_error = 1;
1887                 sblock->generation_error = 1;
1888         }
1889
1890         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
1891                 sblock->header_error = 1;
1892
1893         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1894                    BTRFS_UUID_SIZE))
1895                 sblock->header_error = 1;
1896
1897         len = sctx->nodesize - BTRFS_CSUM_SIZE;
1898         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1899         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1900         index = 0;
1901         for (;;) {
1902                 u64 l = min_t(u64, len, mapped_size);
1903
1904                 crc = btrfs_csum_data(p, crc, l);
1905                 kunmap_atomic(mapped_buffer);
1906                 len -= l;
1907                 if (len == 0)
1908                         break;
1909                 index++;
1910                 BUG_ON(index >= sblock->page_count);
1911                 BUG_ON(!sblock->pagev[index]->page);
1912                 page = sblock->pagev[index]->page;
1913                 mapped_buffer = kmap_atomic(page);
1914                 mapped_size = PAGE_SIZE;
1915                 p = mapped_buffer;
1916         }
1917
1918         btrfs_csum_final(crc, calculated_csum);
1919         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1920                 sblock->checksum_error = 1;
1921
1922         return sblock->header_error || sblock->checksum_error;
1923 }
1924
1925 static int scrub_checksum_super(struct scrub_block *sblock)
1926 {
1927         struct btrfs_super_block *s;
1928         struct scrub_ctx *sctx = sblock->sctx;
1929         u8 calculated_csum[BTRFS_CSUM_SIZE];
1930         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1931         struct page *page;
1932         void *mapped_buffer;
1933         u64 mapped_size;
1934         void *p;
1935         u32 crc = ~(u32)0;
1936         int fail_gen = 0;
1937         int fail_cor = 0;
1938         u64 len;
1939         int index;
1940
1941         BUG_ON(sblock->page_count < 1);
1942         page = sblock->pagev[0]->page;
1943         mapped_buffer = kmap_atomic(page);
1944         s = (struct btrfs_super_block *)mapped_buffer;
1945         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1946
1947         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1948                 ++fail_cor;
1949
1950         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1951                 ++fail_gen;
1952
1953         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1954                 ++fail_cor;
1955
1956         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1957         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1958         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1959         index = 0;
1960         for (;;) {
1961                 u64 l = min_t(u64, len, mapped_size);
1962
1963                 crc = btrfs_csum_data(p, crc, l);
1964                 kunmap_atomic(mapped_buffer);
1965                 len -= l;
1966                 if (len == 0)
1967                         break;
1968                 index++;
1969                 BUG_ON(index >= sblock->page_count);
1970                 BUG_ON(!sblock->pagev[index]->page);
1971                 page = sblock->pagev[index]->page;
1972                 mapped_buffer = kmap_atomic(page);
1973                 mapped_size = PAGE_SIZE;
1974                 p = mapped_buffer;
1975         }
1976
1977         btrfs_csum_final(crc, calculated_csum);
1978         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1979                 ++fail_cor;
1980
1981         if (fail_cor + fail_gen) {
1982                 /*
1983                  * if we find an error in a super block, we just report it.
1984                  * They will get written with the next transaction commit
1985                  * anyway
1986                  */
1987                 spin_lock(&sctx->stat_lock);
1988                 ++sctx->stat.super_errors;
1989                 spin_unlock(&sctx->stat_lock);
1990                 if (fail_cor)
1991                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1992                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1993                 else
1994                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1995                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1996         }
1997
1998         return fail_cor + fail_gen;
1999 }
2000
2001 static void scrub_block_get(struct scrub_block *sblock)
2002 {
2003         atomic_inc(&sblock->refs);
2004 }
2005
2006 static void scrub_block_put(struct scrub_block *sblock)
2007 {
2008         if (atomic_dec_and_test(&sblock->refs)) {
2009                 int i;
2010
2011                 if (sblock->sparity)
2012                         scrub_parity_put(sblock->sparity);
2013
2014                 for (i = 0; i < sblock->page_count; i++)
2015                         scrub_page_put(sblock->pagev[i]);
2016                 kfree(sblock);
2017         }
2018 }
2019
2020 static void scrub_page_get(struct scrub_page *spage)
2021 {
2022         atomic_inc(&spage->refs);
2023 }
2024
2025 static void scrub_page_put(struct scrub_page *spage)
2026 {
2027         if (atomic_dec_and_test(&spage->refs)) {
2028                 if (spage->page)
2029                         __free_page(spage->page);
2030                 kfree(spage);
2031         }
2032 }
2033
2034 static void scrub_submit(struct scrub_ctx *sctx)
2035 {
2036         struct scrub_bio *sbio;
2037
2038         if (sctx->curr == -1)
2039                 return;
2040
2041         sbio = sctx->bios[sctx->curr];
2042         sctx->curr = -1;
2043         scrub_pending_bio_inc(sctx);
2044         btrfsic_submit_bio(READ, sbio->bio);
2045 }
2046
2047 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2048                                     struct scrub_page *spage)
2049 {
2050         struct scrub_block *sblock = spage->sblock;
2051         struct scrub_bio *sbio;
2052         int ret;
2053
2054 again:
2055         /*
2056          * grab a fresh bio or wait for one to become available
2057          */
2058         while (sctx->curr == -1) {
2059                 spin_lock(&sctx->list_lock);
2060                 sctx->curr = sctx->first_free;
2061                 if (sctx->curr != -1) {
2062                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2063                         sctx->bios[sctx->curr]->next_free = -1;
2064                         sctx->bios[sctx->curr]->page_count = 0;
2065                         spin_unlock(&sctx->list_lock);
2066                 } else {
2067                         spin_unlock(&sctx->list_lock);
2068                         wait_event(sctx->list_wait, sctx->first_free != -1);
2069                 }
2070         }
2071         sbio = sctx->bios[sctx->curr];
2072         if (sbio->page_count == 0) {
2073                 struct bio *bio;
2074
2075                 sbio->physical = spage->physical;
2076                 sbio->logical = spage->logical;
2077                 sbio->dev = spage->dev;
2078                 bio = sbio->bio;
2079                 if (!bio) {
2080                         bio = btrfs_io_bio_alloc(GFP_KERNEL,
2081                                         sctx->pages_per_rd_bio);
2082                         if (!bio)
2083                                 return -ENOMEM;
2084                         sbio->bio = bio;
2085                 }
2086
2087                 bio->bi_private = sbio;
2088                 bio->bi_end_io = scrub_bio_end_io;
2089                 bio->bi_bdev = sbio->dev->bdev;
2090                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2091                 sbio->err = 0;
2092         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2093                    spage->physical ||
2094                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2095                    spage->logical ||
2096                    sbio->dev != spage->dev) {
2097                 scrub_submit(sctx);
2098                 goto again;
2099         }
2100
2101         sbio->pagev[sbio->page_count] = spage;
2102         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2103         if (ret != PAGE_SIZE) {
2104                 if (sbio->page_count < 1) {
2105                         bio_put(sbio->bio);
2106                         sbio->bio = NULL;
2107                         return -EIO;
2108                 }
2109                 scrub_submit(sctx);
2110                 goto again;
2111         }
2112
2113         scrub_block_get(sblock); /* one for the page added to the bio */
2114         atomic_inc(&sblock->outstanding_pages);
2115         sbio->page_count++;
2116         if (sbio->page_count == sctx->pages_per_rd_bio)
2117                 scrub_submit(sctx);
2118
2119         return 0;
2120 }
2121
2122 static void scrub_missing_raid56_end_io(struct bio *bio)
2123 {
2124         struct scrub_block *sblock = bio->bi_private;
2125         struct btrfs_fs_info *fs_info = sblock->sctx->dev_root->fs_info;
2126
2127         if (bio->bi_error)
2128                 sblock->no_io_error_seen = 0;
2129
2130         bio_put(bio);
2131
2132         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2133 }
2134
2135 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2136 {
2137         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2138         struct scrub_ctx *sctx = sblock->sctx;
2139         u64 logical;
2140         struct btrfs_device *dev;
2141
2142         logical = sblock->pagev[0]->logical;
2143         dev = sblock->pagev[0]->dev;
2144
2145         if (sblock->no_io_error_seen)
2146                 scrub_recheck_block_checksum(sblock);
2147
2148         if (!sblock->no_io_error_seen) {
2149                 spin_lock(&sctx->stat_lock);
2150                 sctx->stat.read_errors++;
2151                 spin_unlock(&sctx->stat_lock);
2152                 btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
2153                         "IO error rebuilding logical %llu for dev %s",
2154                         logical, rcu_str_deref(dev->name));
2155         } else if (sblock->header_error || sblock->checksum_error) {
2156                 spin_lock(&sctx->stat_lock);
2157                 sctx->stat.uncorrectable_errors++;
2158                 spin_unlock(&sctx->stat_lock);
2159                 btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
2160                         "failed to rebuild valid logical %llu for dev %s",
2161                         logical, rcu_str_deref(dev->name));
2162         } else {
2163                 scrub_write_block_to_dev_replace(sblock);
2164         }
2165
2166         scrub_block_put(sblock);
2167
2168         if (sctx->is_dev_replace &&
2169             atomic_read(&sctx->wr_ctx.flush_all_writes)) {
2170                 mutex_lock(&sctx->wr_ctx.wr_lock);
2171                 scrub_wr_submit(sctx);
2172                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2173         }
2174
2175         scrub_pending_bio_dec(sctx);
2176 }
2177
2178 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2179 {
2180         struct scrub_ctx *sctx = sblock->sctx;
2181         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
2182         u64 length = sblock->page_count * PAGE_SIZE;
2183         u64 logical = sblock->pagev[0]->logical;
2184         struct btrfs_bio *bbio = NULL;
2185         struct bio *bio;
2186         struct btrfs_raid_bio *rbio;
2187         int ret;
2188         int i;
2189
2190         ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
2191                                &bbio, 0, 1);
2192         if (ret || !bbio || !bbio->raid_map)
2193                 goto bbio_out;
2194
2195         if (WARN_ON(!sctx->is_dev_replace ||
2196                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2197                 /*
2198                  * We shouldn't be scrubbing a missing device. Even for dev
2199                  * replace, we should only get here for RAID 5/6. We either
2200                  * managed to mount something with no mirrors remaining or
2201                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2202                  */
2203                 goto bbio_out;
2204         }
2205
2206         bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
2207         if (!bio)
2208                 goto bbio_out;
2209
2210         bio->bi_iter.bi_sector = logical >> 9;
2211         bio->bi_private = sblock;
2212         bio->bi_end_io = scrub_missing_raid56_end_io;
2213
2214         rbio = raid56_alloc_missing_rbio(sctx->dev_root, bio, bbio, length);
2215         if (!rbio)
2216                 goto rbio_out;
2217
2218         for (i = 0; i < sblock->page_count; i++) {
2219                 struct scrub_page *spage = sblock->pagev[i];
2220
2221                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2222         }
2223
2224         btrfs_init_work(&sblock->work, btrfs_scrub_helper,
2225                         scrub_missing_raid56_worker, NULL, NULL);
2226         scrub_block_get(sblock);
2227         scrub_pending_bio_inc(sctx);
2228         raid56_submit_missing_rbio(rbio);
2229         return;
2230
2231 rbio_out:
2232         bio_put(bio);
2233 bbio_out:
2234         btrfs_put_bbio(bbio);
2235         spin_lock(&sctx->stat_lock);
2236         sctx->stat.malloc_errors++;
2237         spin_unlock(&sctx->stat_lock);
2238 }
2239
2240 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2241                        u64 physical, struct btrfs_device *dev, u64 flags,
2242                        u64 gen, int mirror_num, u8 *csum, int force,
2243                        u64 physical_for_dev_replace)
2244 {
2245         struct scrub_block *sblock;
2246         int index;
2247
2248         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2249         if (!sblock) {
2250                 spin_lock(&sctx->stat_lock);
2251                 sctx->stat.malloc_errors++;
2252                 spin_unlock(&sctx->stat_lock);
2253                 return -ENOMEM;
2254         }
2255
2256         /* one ref inside this function, plus one for each page added to
2257          * a bio later on */
2258         atomic_set(&sblock->refs, 1);
2259         sblock->sctx = sctx;
2260         sblock->no_io_error_seen = 1;
2261
2262         for (index = 0; len > 0; index++) {
2263                 struct scrub_page *spage;
2264                 u64 l = min_t(u64, len, PAGE_SIZE);
2265
2266                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2267                 if (!spage) {
2268 leave_nomem:
2269                         spin_lock(&sctx->stat_lock);
2270                         sctx->stat.malloc_errors++;
2271                         spin_unlock(&sctx->stat_lock);
2272                         scrub_block_put(sblock);
2273                         return -ENOMEM;
2274                 }
2275                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2276                 scrub_page_get(spage);
2277                 sblock->pagev[index] = spage;
2278                 spage->sblock = sblock;
2279                 spage->dev = dev;
2280                 spage->flags = flags;
2281                 spage->generation = gen;
2282                 spage->logical = logical;
2283                 spage->physical = physical;
2284                 spage->physical_for_dev_replace = physical_for_dev_replace;
2285                 spage->mirror_num = mirror_num;
2286                 if (csum) {
2287                         spage->have_csum = 1;
2288                         memcpy(spage->csum, csum, sctx->csum_size);
2289                 } else {
2290                         spage->have_csum = 0;
2291                 }
2292                 sblock->page_count++;
2293                 spage->page = alloc_page(GFP_KERNEL);
2294                 if (!spage->page)
2295                         goto leave_nomem;
2296                 len -= l;
2297                 logical += l;
2298                 physical += l;
2299                 physical_for_dev_replace += l;
2300         }
2301
2302         WARN_ON(sblock->page_count == 0);
2303         if (dev->missing) {
2304                 /*
2305                  * This case should only be hit for RAID 5/6 device replace. See
2306                  * the comment in scrub_missing_raid56_pages() for details.
2307                  */
2308                 scrub_missing_raid56_pages(sblock);
2309         } else {
2310                 for (index = 0; index < sblock->page_count; index++) {
2311                         struct scrub_page *spage = sblock->pagev[index];
2312                         int ret;
2313
2314                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2315                         if (ret) {
2316                                 scrub_block_put(sblock);
2317                                 return ret;
2318                         }
2319                 }
2320
2321                 if (force)
2322                         scrub_submit(sctx);
2323         }
2324
2325         /* last one frees, either here or in bio completion for last page */
2326         scrub_block_put(sblock);
2327         return 0;
2328 }
2329
2330 static void scrub_bio_end_io(struct bio *bio)
2331 {
2332         struct scrub_bio *sbio = bio->bi_private;
2333         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
2334
2335         sbio->err = bio->bi_error;
2336         sbio->bio = bio;
2337
2338         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2339 }
2340
2341 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2342 {
2343         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2344         struct scrub_ctx *sctx = sbio->sctx;
2345         int i;
2346
2347         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2348         if (sbio->err) {
2349                 for (i = 0; i < sbio->page_count; i++) {
2350                         struct scrub_page *spage = sbio->pagev[i];
2351
2352                         spage->io_error = 1;
2353                         spage->sblock->no_io_error_seen = 0;
2354                 }
2355         }
2356
2357         /* now complete the scrub_block items that have all pages completed */
2358         for (i = 0; i < sbio->page_count; i++) {
2359                 struct scrub_page *spage = sbio->pagev[i];
2360                 struct scrub_block *sblock = spage->sblock;
2361
2362                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2363                         scrub_block_complete(sblock);
2364                 scrub_block_put(sblock);
2365         }
2366
2367         bio_put(sbio->bio);
2368         sbio->bio = NULL;
2369         spin_lock(&sctx->list_lock);
2370         sbio->next_free = sctx->first_free;
2371         sctx->first_free = sbio->index;
2372         spin_unlock(&sctx->list_lock);
2373
2374         if (sctx->is_dev_replace &&
2375             atomic_read(&sctx->wr_ctx.flush_all_writes)) {
2376                 mutex_lock(&sctx->wr_ctx.wr_lock);
2377                 scrub_wr_submit(sctx);
2378                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2379         }
2380
2381         scrub_pending_bio_dec(sctx);
2382 }
2383
2384 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2385                                        unsigned long *bitmap,
2386                                        u64 start, u64 len)
2387 {
2388         u32 offset;
2389         int nsectors;
2390         int sectorsize = sparity->sctx->dev_root->sectorsize;
2391
2392         if (len >= sparity->stripe_len) {
2393                 bitmap_set(bitmap, 0, sparity->nsectors);
2394                 return;
2395         }
2396
2397         start -= sparity->logic_start;
2398         start = div_u64_rem(start, sparity->stripe_len, &offset);
2399         offset /= sectorsize;
2400         nsectors = (int)len / sectorsize;
2401
2402         if (offset + nsectors <= sparity->nsectors) {
2403                 bitmap_set(bitmap, offset, nsectors);
2404                 return;
2405         }
2406
2407         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2408         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2409 }
2410
2411 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2412                                                    u64 start, u64 len)
2413 {
2414         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2415 }
2416
2417 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2418                                                   u64 start, u64 len)
2419 {
2420         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2421 }
2422
2423 static void scrub_block_complete(struct scrub_block *sblock)
2424 {
2425         int corrupted = 0;
2426
2427         if (!sblock->no_io_error_seen) {
2428                 corrupted = 1;
2429                 scrub_handle_errored_block(sblock);
2430         } else {
2431                 /*
2432                  * if has checksum error, write via repair mechanism in
2433                  * dev replace case, otherwise write here in dev replace
2434                  * case.
2435                  */
2436                 corrupted = scrub_checksum(sblock);
2437                 if (!corrupted && sblock->sctx->is_dev_replace)
2438                         scrub_write_block_to_dev_replace(sblock);
2439         }
2440
2441         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2442                 u64 start = sblock->pagev[0]->logical;
2443                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2444                           PAGE_SIZE;
2445
2446                 scrub_parity_mark_sectors_error(sblock->sparity,
2447                                                 start, end - start);
2448         }
2449 }
2450
2451 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2452 {
2453         struct btrfs_ordered_sum *sum = NULL;
2454         unsigned long index;
2455         unsigned long num_sectors;
2456
2457         while (!list_empty(&sctx->csum_list)) {
2458                 sum = list_first_entry(&sctx->csum_list,
2459                                        struct btrfs_ordered_sum, list);
2460                 if (sum->bytenr > logical)
2461                         return 0;
2462                 if (sum->bytenr + sum->len > logical)
2463                         break;
2464
2465                 ++sctx->stat.csum_discards;
2466                 list_del(&sum->list);
2467                 kfree(sum);
2468                 sum = NULL;
2469         }
2470         if (!sum)
2471                 return 0;
2472
2473         index = ((u32)(logical - sum->bytenr)) / sctx->sectorsize;
2474         num_sectors = sum->len / sctx->sectorsize;
2475         memcpy(csum, sum->sums + index, sctx->csum_size);
2476         if (index == num_sectors - 1) {
2477                 list_del(&sum->list);
2478                 kfree(sum);
2479         }
2480         return 1;
2481 }
2482
2483 /* scrub extent tries to collect up to 64 kB for each bio */
2484 static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
2485                         u64 physical, struct btrfs_device *dev, u64 flags,
2486                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2487 {
2488         int ret;
2489         u8 csum[BTRFS_CSUM_SIZE];
2490         u32 blocksize;
2491
2492         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2493                 blocksize = sctx->sectorsize;
2494                 spin_lock(&sctx->stat_lock);
2495                 sctx->stat.data_extents_scrubbed++;
2496                 sctx->stat.data_bytes_scrubbed += len;
2497                 spin_unlock(&sctx->stat_lock);
2498         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2499                 blocksize = sctx->nodesize;
2500                 spin_lock(&sctx->stat_lock);
2501                 sctx->stat.tree_extents_scrubbed++;
2502                 sctx->stat.tree_bytes_scrubbed += len;
2503                 spin_unlock(&sctx->stat_lock);
2504         } else {
2505                 blocksize = sctx->sectorsize;
2506                 WARN_ON(1);
2507         }
2508
2509         while (len) {
2510                 u64 l = min_t(u64, len, blocksize);
2511                 int have_csum = 0;
2512
2513                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2514                         /* push csums to sbio */
2515                         have_csum = scrub_find_csum(sctx, logical, csum);
2516                         if (have_csum == 0)
2517                                 ++sctx->stat.no_csum;
2518                         if (sctx->is_dev_replace && !have_csum) {
2519                                 ret = copy_nocow_pages(sctx, logical, l,
2520                                                        mirror_num,
2521                                                       physical_for_dev_replace);
2522                                 goto behind_scrub_pages;
2523                         }
2524                 }
2525                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2526                                   mirror_num, have_csum ? csum : NULL, 0,
2527                                   physical_for_dev_replace);
2528 behind_scrub_pages:
2529                 if (ret)
2530                         return ret;
2531                 len -= l;
2532                 logical += l;
2533                 physical += l;
2534                 physical_for_dev_replace += l;
2535         }
2536         return 0;
2537 }
2538
2539 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2540                                   u64 logical, u64 len,
2541                                   u64 physical, struct btrfs_device *dev,
2542                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2543 {
2544         struct scrub_ctx *sctx = sparity->sctx;
2545         struct scrub_block *sblock;
2546         int index;
2547
2548         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2549         if (!sblock) {
2550                 spin_lock(&sctx->stat_lock);
2551                 sctx->stat.malloc_errors++;
2552                 spin_unlock(&sctx->stat_lock);
2553                 return -ENOMEM;
2554         }
2555
2556         /* one ref inside this function, plus one for each page added to
2557          * a bio later on */
2558         atomic_set(&sblock->refs, 1);
2559         sblock->sctx = sctx;
2560         sblock->no_io_error_seen = 1;
2561         sblock->sparity = sparity;
2562         scrub_parity_get(sparity);
2563
2564         for (index = 0; len > 0; index++) {
2565                 struct scrub_page *spage;
2566                 u64 l = min_t(u64, len, PAGE_SIZE);
2567
2568                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2569                 if (!spage) {
2570 leave_nomem:
2571                         spin_lock(&sctx->stat_lock);
2572                         sctx->stat.malloc_errors++;
2573                         spin_unlock(&sctx->stat_lock);
2574                         scrub_block_put(sblock);
2575                         return -ENOMEM;
2576                 }
2577                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2578                 /* For scrub block */
2579                 scrub_page_get(spage);
2580                 sblock->pagev[index] = spage;
2581                 /* For scrub parity */
2582                 scrub_page_get(spage);
2583                 list_add_tail(&spage->list, &sparity->spages);
2584                 spage->sblock = sblock;
2585                 spage->dev = dev;
2586                 spage->flags = flags;
2587                 spage->generation = gen;
2588                 spage->logical = logical;
2589                 spage->physical = physical;
2590                 spage->mirror_num = mirror_num;
2591                 if (csum) {
2592                         spage->have_csum = 1;
2593                         memcpy(spage->csum, csum, sctx->csum_size);
2594                 } else {
2595                         spage->have_csum = 0;
2596                 }
2597                 sblock->page_count++;
2598                 spage->page = alloc_page(GFP_KERNEL);
2599                 if (!spage->page)
2600                         goto leave_nomem;
2601                 len -= l;
2602                 logical += l;
2603                 physical += l;
2604         }
2605
2606         WARN_ON(sblock->page_count == 0);
2607         for (index = 0; index < sblock->page_count; index++) {
2608                 struct scrub_page *spage = sblock->pagev[index];
2609                 int ret;
2610
2611                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2612                 if (ret) {
2613                         scrub_block_put(sblock);
2614                         return ret;
2615                 }
2616         }
2617
2618         /* last one frees, either here or in bio completion for last page */
2619         scrub_block_put(sblock);
2620         return 0;
2621 }
2622
2623 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2624                                    u64 logical, u64 len,
2625                                    u64 physical, struct btrfs_device *dev,
2626                                    u64 flags, u64 gen, int mirror_num)
2627 {
2628         struct scrub_ctx *sctx = sparity->sctx;
2629         int ret;
2630         u8 csum[BTRFS_CSUM_SIZE];
2631         u32 blocksize;
2632
2633         if (dev->missing) {
2634                 scrub_parity_mark_sectors_error(sparity, logical, len);
2635                 return 0;
2636         }
2637
2638         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2639                 blocksize = sctx->sectorsize;
2640         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2641                 blocksize = sctx->nodesize;
2642         } else {
2643                 blocksize = sctx->sectorsize;
2644                 WARN_ON(1);
2645         }
2646
2647         while (len) {
2648                 u64 l = min_t(u64, len, blocksize);
2649                 int have_csum = 0;
2650
2651                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2652                         /* push csums to sbio */
2653                         have_csum = scrub_find_csum(sctx, logical, csum);
2654                         if (have_csum == 0)
2655                                 goto skip;
2656                 }
2657                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2658                                              flags, gen, mirror_num,
2659                                              have_csum ? csum : NULL);
2660                 if (ret)
2661                         return ret;
2662 skip:
2663                 len -= l;
2664                 logical += l;
2665                 physical += l;
2666         }
2667         return 0;
2668 }
2669
2670 /*
2671  * Given a physical address, this will calculate it's
2672  * logical offset. if this is a parity stripe, it will return
2673  * the most left data stripe's logical offset.
2674  *
2675  * return 0 if it is a data stripe, 1 means parity stripe.
2676  */
2677 static int get_raid56_logic_offset(u64 physical, int num,
2678                                    struct map_lookup *map, u64 *offset,
2679                                    u64 *stripe_start)
2680 {
2681         int i;
2682         int j = 0;
2683         u64 stripe_nr;
2684         u64 last_offset;
2685         u32 stripe_index;
2686         u32 rot;
2687
2688         last_offset = (physical - map->stripes[num].physical) *
2689                       nr_data_stripes(map);
2690         if (stripe_start)
2691                 *stripe_start = last_offset;
2692
2693         *offset = last_offset;
2694         for (i = 0; i < nr_data_stripes(map); i++) {
2695                 *offset = last_offset + i * map->stripe_len;
2696
2697                 stripe_nr = div_u64(*offset, map->stripe_len);
2698                 stripe_nr = div_u64(stripe_nr, nr_data_stripes(map));
2699
2700                 /* Work out the disk rotation on this stripe-set */
2701                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2702                 /* calculate which stripe this data locates */
2703                 rot += i;
2704                 stripe_index = rot % map->num_stripes;
2705                 if (stripe_index == num)
2706                         return 0;
2707                 if (stripe_index < num)
2708                         j++;
2709         }
2710         *offset = last_offset + j * map->stripe_len;
2711         return 1;
2712 }
2713
2714 static void scrub_free_parity(struct scrub_parity *sparity)
2715 {
2716         struct scrub_ctx *sctx = sparity->sctx;
2717         struct scrub_page *curr, *next;
2718         int nbits;
2719
2720         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2721         if (nbits) {
2722                 spin_lock(&sctx->stat_lock);
2723                 sctx->stat.read_errors += nbits;
2724                 sctx->stat.uncorrectable_errors += nbits;
2725                 spin_unlock(&sctx->stat_lock);
2726         }
2727
2728         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2729                 list_del_init(&curr->list);
2730                 scrub_page_put(curr);
2731         }
2732
2733         kfree(sparity);
2734 }
2735
2736 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2737 {
2738         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2739                                                     work);
2740         struct scrub_ctx *sctx = sparity->sctx;
2741
2742         scrub_free_parity(sparity);
2743         scrub_pending_bio_dec(sctx);
2744 }
2745
2746 static void scrub_parity_bio_endio(struct bio *bio)
2747 {
2748         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
2749
2750         if (bio->bi_error)
2751                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2752                           sparity->nsectors);
2753
2754         bio_put(bio);
2755
2756         btrfs_init_work(&sparity->work, btrfs_scrubparity_helper,
2757                         scrub_parity_bio_endio_worker, NULL, NULL);
2758         btrfs_queue_work(sparity->sctx->dev_root->fs_info->scrub_parity_workers,
2759                          &sparity->work);
2760 }
2761
2762 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
2763 {
2764         struct scrub_ctx *sctx = sparity->sctx;
2765         struct bio *bio;
2766         struct btrfs_raid_bio *rbio;
2767         struct scrub_page *spage;
2768         struct btrfs_bio *bbio = NULL;
2769         u64 length;
2770         int ret;
2771
2772         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
2773                            sparity->nsectors))
2774                 goto out;
2775
2776         length = sparity->logic_end - sparity->logic_start;
2777         ret = btrfs_map_sblock(sctx->dev_root->fs_info, WRITE,
2778                                sparity->logic_start,
2779                                &length, &bbio, 0, 1);
2780         if (ret || !bbio || !bbio->raid_map)
2781                 goto bbio_out;
2782
2783         bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
2784         if (!bio)
2785                 goto bbio_out;
2786
2787         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
2788         bio->bi_private = sparity;
2789         bio->bi_end_io = scrub_parity_bio_endio;
2790
2791         rbio = raid56_parity_alloc_scrub_rbio(sctx->dev_root, bio, bbio,
2792                                               length, sparity->scrub_dev,
2793                                               sparity->dbitmap,
2794                                               sparity->nsectors);
2795         if (!rbio)
2796                 goto rbio_out;
2797
2798         list_for_each_entry(spage, &sparity->spages, list)
2799                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2800
2801         scrub_pending_bio_inc(sctx);
2802         raid56_parity_submit_scrub_rbio(rbio);
2803         return;
2804
2805 rbio_out:
2806         bio_put(bio);
2807 bbio_out:
2808         btrfs_put_bbio(bbio);
2809         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2810                   sparity->nsectors);
2811         spin_lock(&sctx->stat_lock);
2812         sctx->stat.malloc_errors++;
2813         spin_unlock(&sctx->stat_lock);
2814 out:
2815         scrub_free_parity(sparity);
2816 }
2817
2818 static inline int scrub_calc_parity_bitmap_len(int nsectors)
2819 {
2820         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
2821 }
2822
2823 static void scrub_parity_get(struct scrub_parity *sparity)
2824 {
2825         atomic_inc(&sparity->refs);
2826 }
2827
2828 static void scrub_parity_put(struct scrub_parity *sparity)
2829 {
2830         if (!atomic_dec_and_test(&sparity->refs))
2831                 return;
2832
2833         scrub_parity_check_and_repair(sparity);
2834 }
2835
2836 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
2837                                                   struct map_lookup *map,
2838                                                   struct btrfs_device *sdev,
2839                                                   struct btrfs_path *path,
2840                                                   u64 logic_start,
2841                                                   u64 logic_end)
2842 {
2843         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
2844         struct btrfs_root *root = fs_info->extent_root;
2845         struct btrfs_root *csum_root = fs_info->csum_root;
2846         struct btrfs_extent_item *extent;
2847         struct btrfs_bio *bbio = NULL;
2848         u64 flags;
2849         int ret;
2850         int slot;
2851         struct extent_buffer *l;
2852         struct btrfs_key key;
2853         u64 generation;
2854         u64 extent_logical;
2855         u64 extent_physical;
2856         u64 extent_len;
2857         u64 mapped_length;
2858         struct btrfs_device *extent_dev;
2859         struct scrub_parity *sparity;
2860         int nsectors;
2861         int bitmap_len;
2862         int extent_mirror_num;
2863         int stop_loop = 0;
2864
2865         nsectors = div_u64(map->stripe_len, root->sectorsize);
2866         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
2867         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
2868                           GFP_NOFS);
2869         if (!sparity) {
2870                 spin_lock(&sctx->stat_lock);
2871                 sctx->stat.malloc_errors++;
2872                 spin_unlock(&sctx->stat_lock);
2873                 return -ENOMEM;
2874         }
2875
2876         sparity->stripe_len = map->stripe_len;
2877         sparity->nsectors = nsectors;
2878         sparity->sctx = sctx;
2879         sparity->scrub_dev = sdev;
2880         sparity->logic_start = logic_start;
2881         sparity->logic_end = logic_end;
2882         atomic_set(&sparity->refs, 1);
2883         INIT_LIST_HEAD(&sparity->spages);
2884         sparity->dbitmap = sparity->bitmap;
2885         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
2886
2887         ret = 0;
2888         while (logic_start < logic_end) {
2889                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2890                         key.type = BTRFS_METADATA_ITEM_KEY;
2891                 else
2892                         key.type = BTRFS_EXTENT_ITEM_KEY;
2893                 key.objectid = logic_start;
2894                 key.offset = (u64)-1;
2895
2896                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2897                 if (ret < 0)
2898                         goto out;
2899
2900                 if (ret > 0) {
2901                         ret = btrfs_previous_extent_item(root, path, 0);
2902                         if (ret < 0)
2903                                 goto out;
2904                         if (ret > 0) {
2905                                 btrfs_release_path(path);
2906                                 ret = btrfs_search_slot(NULL, root, &key,
2907                                                         path, 0, 0);
2908                                 if (ret < 0)
2909                                         goto out;
2910                         }
2911                 }
2912
2913                 stop_loop = 0;
2914                 while (1) {
2915                         u64 bytes;
2916
2917                         l = path->nodes[0];
2918                         slot = path->slots[0];
2919                         if (slot >= btrfs_header_nritems(l)) {
2920                                 ret = btrfs_next_leaf(root, path);
2921                                 if (ret == 0)
2922                                         continue;
2923                                 if (ret < 0)
2924                                         goto out;
2925
2926                                 stop_loop = 1;
2927                                 break;
2928                         }
2929                         btrfs_item_key_to_cpu(l, &key, slot);
2930
2931                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2932                             key.type != BTRFS_METADATA_ITEM_KEY)
2933                                 goto next;
2934
2935                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2936                                 bytes = root->nodesize;
2937                         else
2938                                 bytes = key.offset;
2939
2940                         if (key.objectid + bytes <= logic_start)
2941                                 goto next;
2942
2943                         if (key.objectid >= logic_end) {
2944                                 stop_loop = 1;
2945                                 break;
2946                         }
2947
2948                         while (key.objectid >= logic_start + map->stripe_len)
2949                                 logic_start += map->stripe_len;
2950
2951                         extent = btrfs_item_ptr(l, slot,
2952                                                 struct btrfs_extent_item);
2953                         flags = btrfs_extent_flags(l, extent);
2954                         generation = btrfs_extent_generation(l, extent);
2955
2956                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
2957                             (key.objectid < logic_start ||
2958                              key.objectid + bytes >
2959                              logic_start + map->stripe_len)) {
2960                                 btrfs_err(fs_info, "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
2961                                           key.objectid, logic_start);
2962                                 spin_lock(&sctx->stat_lock);
2963                                 sctx->stat.uncorrectable_errors++;
2964                                 spin_unlock(&sctx->stat_lock);
2965                                 goto next;
2966                         }
2967 again:
2968                         extent_logical = key.objectid;
2969                         extent_len = bytes;
2970
2971                         if (extent_logical < logic_start) {
2972                                 extent_len -= logic_start - extent_logical;
2973                                 extent_logical = logic_start;
2974                         }
2975
2976                         if (extent_logical + extent_len >
2977                             logic_start + map->stripe_len)
2978                                 extent_len = logic_start + map->stripe_len -
2979                                              extent_logical;
2980
2981                         scrub_parity_mark_sectors_data(sparity, extent_logical,
2982                                                        extent_len);
2983
2984                         mapped_length = extent_len;
2985                         bbio = NULL;
2986                         ret = btrfs_map_block(fs_info, READ, extent_logical,
2987                                               &mapped_length, &bbio, 0);
2988                         if (!ret) {
2989                                 if (!bbio || mapped_length < extent_len)
2990                                         ret = -EIO;
2991                         }
2992                         if (ret) {
2993                                 btrfs_put_bbio(bbio);
2994                                 goto out;
2995                         }
2996                         extent_physical = bbio->stripes[0].physical;
2997                         extent_mirror_num = bbio->mirror_num;
2998                         extent_dev = bbio->stripes[0].dev;
2999                         btrfs_put_bbio(bbio);
3000
3001                         ret = btrfs_lookup_csums_range(csum_root,
3002                                                 extent_logical,
3003                                                 extent_logical + extent_len - 1,
3004                                                 &sctx->csum_list, 1);
3005                         if (ret)
3006                                 goto out;
3007
3008                         ret = scrub_extent_for_parity(sparity, extent_logical,
3009                                                       extent_len,
3010                                                       extent_physical,
3011                                                       extent_dev, flags,
3012                                                       generation,
3013                                                       extent_mirror_num);
3014
3015                         scrub_free_csums(sctx);
3016
3017                         if (ret)
3018                                 goto out;
3019
3020                         if (extent_logical + extent_len <
3021                             key.objectid + bytes) {
3022                                 logic_start += map->stripe_len;
3023
3024                                 if (logic_start >= logic_end) {
3025                                         stop_loop = 1;
3026                                         break;
3027                                 }
3028
3029                                 if (logic_start < key.objectid + bytes) {
3030                                         cond_resched();
3031                                         goto again;
3032                                 }
3033                         }
3034 next:
3035                         path->slots[0]++;
3036                 }
3037
3038                 btrfs_release_path(path);
3039
3040                 if (stop_loop)
3041                         break;
3042
3043                 logic_start += map->stripe_len;
3044         }
3045 out:
3046         if (ret < 0)
3047                 scrub_parity_mark_sectors_error(sparity, logic_start,
3048                                                 logic_end - logic_start);
3049         scrub_parity_put(sparity);
3050         scrub_submit(sctx);
3051         mutex_lock(&sctx->wr_ctx.wr_lock);
3052         scrub_wr_submit(sctx);
3053         mutex_unlock(&sctx->wr_ctx.wr_lock);
3054
3055         btrfs_release_path(path);
3056         return ret < 0 ? ret : 0;
3057 }
3058
3059 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3060                                            struct map_lookup *map,
3061                                            struct btrfs_device *scrub_dev,
3062                                            int num, u64 base, u64 length,
3063                                            int is_dev_replace)
3064 {
3065         struct btrfs_path *path, *ppath;
3066         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
3067         struct btrfs_root *root = fs_info->extent_root;
3068         struct btrfs_root *csum_root = fs_info->csum_root;
3069         struct btrfs_extent_item *extent;
3070         struct blk_plug plug;
3071         u64 flags;
3072         int ret;
3073         int slot;
3074         u64 nstripes;
3075         struct extent_buffer *l;
3076         u64 physical;
3077         u64 logical;
3078         u64 logic_end;
3079         u64 physical_end;
3080         u64 generation;
3081         int mirror_num;
3082         struct reada_control *reada1;
3083         struct reada_control *reada2;
3084         struct btrfs_key key;
3085         struct btrfs_key key_end;
3086         u64 increment = map->stripe_len;
3087         u64 offset;
3088         u64 extent_logical;
3089         u64 extent_physical;
3090         u64 extent_len;
3091         u64 stripe_logical;
3092         u64 stripe_end;
3093         struct btrfs_device *extent_dev;
3094         int extent_mirror_num;
3095         int stop_loop = 0;
3096
3097         physical = map->stripes[num].physical;
3098         offset = 0;
3099         nstripes = div_u64(length, map->stripe_len);
3100         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3101                 offset = map->stripe_len * num;
3102                 increment = map->stripe_len * map->num_stripes;
3103                 mirror_num = 1;
3104         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3105                 int factor = map->num_stripes / map->sub_stripes;
3106                 offset = map->stripe_len * (num / map->sub_stripes);
3107                 increment = map->stripe_len * factor;
3108                 mirror_num = num % map->sub_stripes + 1;
3109         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
3110                 increment = map->stripe_len;
3111                 mirror_num = num % map->num_stripes + 1;
3112         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3113                 increment = map->stripe_len;
3114                 mirror_num = num % map->num_stripes + 1;
3115         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3116                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3117                 increment = map->stripe_len * nr_data_stripes(map);
3118                 mirror_num = 1;
3119         } else {
3120                 increment = map->stripe_len;
3121                 mirror_num = 1;
3122         }
3123
3124         path = btrfs_alloc_path();
3125         if (!path)
3126                 return -ENOMEM;
3127
3128         ppath = btrfs_alloc_path();
3129         if (!ppath) {
3130                 btrfs_free_path(path);
3131                 return -ENOMEM;
3132         }
3133
3134         /*
3135          * work on commit root. The related disk blocks are static as
3136          * long as COW is applied. This means, it is save to rewrite
3137          * them to repair disk errors without any race conditions
3138          */
3139         path->search_commit_root = 1;
3140         path->skip_locking = 1;
3141
3142         ppath->search_commit_root = 1;
3143         ppath->skip_locking = 1;
3144         /*
3145          * trigger the readahead for extent tree csum tree and wait for
3146          * completion. During readahead, the scrub is officially paused
3147          * to not hold off transaction commits
3148          */
3149         logical = base + offset;
3150         physical_end = physical + nstripes * map->stripe_len;
3151         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3152                 get_raid56_logic_offset(physical_end, num,
3153                                         map, &logic_end, NULL);
3154                 logic_end += base;
3155         } else {
3156                 logic_end = logical + increment * nstripes;
3157         }
3158         wait_event(sctx->list_wait,
3159                    atomic_read(&sctx->bios_in_flight) == 0);
3160         scrub_blocked_if_needed(fs_info);
3161
3162         /* FIXME it might be better to start readahead at commit root */
3163         key.objectid = logical;
3164         key.type = BTRFS_EXTENT_ITEM_KEY;
3165         key.offset = (u64)0;
3166         key_end.objectid = logic_end;
3167         key_end.type = BTRFS_METADATA_ITEM_KEY;
3168         key_end.offset = (u64)-1;
3169         reada1 = btrfs_reada_add(root, &key, &key_end);
3170
3171         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3172         key.type = BTRFS_EXTENT_CSUM_KEY;
3173         key.offset = logical;
3174         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3175         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3176         key_end.offset = logic_end;
3177         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3178
3179         if (!IS_ERR(reada1))
3180                 btrfs_reada_wait(reada1);
3181         if (!IS_ERR(reada2))
3182                 btrfs_reada_wait(reada2);
3183
3184
3185         /*
3186          * collect all data csums for the stripe to avoid seeking during
3187          * the scrub. This might currently (crc32) end up to be about 1MB
3188          */
3189         blk_start_plug(&plug);
3190
3191         /*
3192          * now find all extents for each stripe and scrub them
3193          */
3194         ret = 0;
3195         while (physical < physical_end) {
3196                 /*
3197                  * canceled?
3198                  */
3199                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3200                     atomic_read(&sctx->cancel_req)) {
3201                         ret = -ECANCELED;
3202                         goto out;
3203                 }
3204                 /*
3205                  * check to see if we have to pause
3206                  */
3207                 if (atomic_read(&fs_info->scrub_pause_req)) {
3208                         /* push queued extents */
3209                         atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
3210                         scrub_submit(sctx);
3211                         mutex_lock(&sctx->wr_ctx.wr_lock);
3212                         scrub_wr_submit(sctx);
3213                         mutex_unlock(&sctx->wr_ctx.wr_lock);
3214                         wait_event(sctx->list_wait,
3215                                    atomic_read(&sctx->bios_in_flight) == 0);
3216                         atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
3217                         scrub_blocked_if_needed(fs_info);
3218                 }
3219
3220                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3221                         ret = get_raid56_logic_offset(physical, num, map,
3222                                                       &logical,
3223                                                       &stripe_logical);
3224                         logical += base;
3225                         if (ret) {
3226                                 /* it is parity strip */
3227                                 stripe_logical += base;
3228                                 stripe_end = stripe_logical + increment;
3229                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3230                                                           ppath, stripe_logical,
3231                                                           stripe_end);
3232                                 if (ret)
3233                                         goto out;
3234                                 goto skip;
3235                         }
3236                 }
3237
3238                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3239                         key.type = BTRFS_METADATA_ITEM_KEY;
3240                 else
3241                         key.type = BTRFS_EXTENT_ITEM_KEY;
3242                 key.objectid = logical;
3243                 key.offset = (u64)-1;
3244
3245                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3246                 if (ret < 0)
3247                         goto out;
3248
3249                 if (ret > 0) {
3250                         ret = btrfs_previous_extent_item(root, path, 0);
3251                         if (ret < 0)
3252                                 goto out;
3253                         if (ret > 0) {
3254                                 /* there's no smaller item, so stick with the
3255                                  * larger one */
3256                                 btrfs_release_path(path);
3257                                 ret = btrfs_search_slot(NULL, root, &key,
3258                                                         path, 0, 0);
3259                                 if (ret < 0)
3260                                         goto out;
3261                         }
3262                 }
3263
3264                 stop_loop = 0;
3265                 while (1) {
3266                         u64 bytes;
3267
3268                         l = path->nodes[0];
3269                         slot = path->slots[0];
3270                         if (slot >= btrfs_header_nritems(l)) {
3271                                 ret = btrfs_next_leaf(root, path);
3272                                 if (ret == 0)
3273                                         continue;
3274                                 if (ret < 0)
3275                                         goto out;
3276
3277                                 stop_loop = 1;
3278                                 break;
3279                         }
3280                         btrfs_item_key_to_cpu(l, &key, slot);
3281
3282                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3283                             key.type != BTRFS_METADATA_ITEM_KEY)
3284                                 goto next;
3285
3286                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3287                                 bytes = root->nodesize;
3288                         else
3289                                 bytes = key.offset;
3290
3291                         if (key.objectid + bytes <= logical)
3292                                 goto next;
3293
3294                         if (key.objectid >= logical + map->stripe_len) {
3295                                 /* out of this device extent */
3296                                 if (key.objectid >= logic_end)
3297                                         stop_loop = 1;
3298                                 break;
3299                         }
3300
3301                         extent = btrfs_item_ptr(l, slot,
3302                                                 struct btrfs_extent_item);
3303                         flags = btrfs_extent_flags(l, extent);
3304                         generation = btrfs_extent_generation(l, extent);
3305
3306                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3307                             (key.objectid < logical ||
3308                              key.objectid + bytes >
3309                              logical + map->stripe_len)) {
3310                                 btrfs_err(fs_info,
3311                                            "scrub: tree block %llu spanning "
3312                                            "stripes, ignored. logical=%llu",
3313                                        key.objectid, logical);
3314                                 spin_lock(&sctx->stat_lock);
3315                                 sctx->stat.uncorrectable_errors++;
3316                                 spin_unlock(&sctx->stat_lock);
3317                                 goto next;
3318                         }
3319
3320 again:
3321                         extent_logical = key.objectid;
3322                         extent_len = bytes;
3323
3324                         /*
3325                          * trim extent to this stripe
3326                          */
3327                         if (extent_logical < logical) {
3328                                 extent_len -= logical - extent_logical;
3329                                 extent_logical = logical;
3330                         }
3331                         if (extent_logical + extent_len >
3332                             logical + map->stripe_len) {
3333                                 extent_len = logical + map->stripe_len -
3334                                              extent_logical;
3335                         }
3336
3337                         extent_physical = extent_logical - logical + physical;
3338                         extent_dev = scrub_dev;
3339                         extent_mirror_num = mirror_num;
3340                         if (is_dev_replace)
3341                                 scrub_remap_extent(fs_info, extent_logical,
3342                                                    extent_len, &extent_physical,
3343                                                    &extent_dev,
3344                                                    &extent_mirror_num);
3345
3346                         ret = btrfs_lookup_csums_range(csum_root,
3347                                                        extent_logical,
3348                                                        extent_logical +
3349                                                        extent_len - 1,
3350                                                        &sctx->csum_list, 1);
3351                         if (ret)
3352                                 goto out;
3353
3354                         ret = scrub_extent(sctx, extent_logical, extent_len,
3355                                            extent_physical, extent_dev, flags,
3356                                            generation, extent_mirror_num,
3357                                            extent_logical - logical + physical);
3358
3359                         scrub_free_csums(sctx);
3360
3361                         if (ret)
3362                                 goto out;
3363
3364                         if (extent_logical + extent_len <
3365                             key.objectid + bytes) {
3366                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3367                                         /*
3368                                          * loop until we find next data stripe
3369                                          * or we have finished all stripes.
3370                                          */
3371 loop:
3372                                         physical += map->stripe_len;
3373                                         ret = get_raid56_logic_offset(physical,
3374                                                         num, map, &logical,
3375                                                         &stripe_logical);
3376                                         logical += base;
3377
3378                                         if (ret && physical < physical_end) {
3379                                                 stripe_logical += base;
3380                                                 stripe_end = stripe_logical +
3381                                                                 increment;
3382                                                 ret = scrub_raid56_parity(sctx,
3383                                                         map, scrub_dev, ppath,
3384                                                         stripe_logical,
3385                                                         stripe_end);
3386                                                 if (ret)
3387                                                         goto out;
3388                                                 goto loop;
3389                                         }
3390                                 } else {
3391                                         physical += map->stripe_len;
3392                                         logical += increment;
3393                                 }
3394                                 if (logical < key.objectid + bytes) {
3395                                         cond_resched();
3396                                         goto again;
3397                                 }
3398
3399                                 if (physical >= physical_end) {
3400                                         stop_loop = 1;
3401                                         break;
3402                                 }
3403                         }
3404 next:
3405                         path->slots[0]++;
3406                 }
3407                 btrfs_release_path(path);
3408 skip:
3409                 logical += increment;
3410                 physical += map->stripe_len;
3411                 spin_lock(&sctx->stat_lock);
3412                 if (stop_loop)
3413                         sctx->stat.last_physical = map->stripes[num].physical +
3414                                                    length;
3415                 else
3416                         sctx->stat.last_physical = physical;
3417                 spin_unlock(&sctx->stat_lock);
3418                 if (stop_loop)
3419                         break;
3420         }
3421 out:
3422         /* push queued extents */
3423         scrub_submit(sctx);
3424         mutex_lock(&sctx->wr_ctx.wr_lock);
3425         scrub_wr_submit(sctx);
3426         mutex_unlock(&sctx->wr_ctx.wr_lock);
3427
3428         blk_finish_plug(&plug);
3429         btrfs_free_path(path);
3430         btrfs_free_path(ppath);
3431         return ret < 0 ? ret : 0;
3432 }
3433
3434 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3435                                           struct btrfs_device *scrub_dev,
3436                                           u64 chunk_offset, u64 length,
3437                                           u64 dev_offset,
3438                                           struct btrfs_block_group_cache *cache,
3439                                           int is_dev_replace)
3440 {
3441         struct btrfs_mapping_tree *map_tree =
3442                 &sctx->dev_root->fs_info->mapping_tree;
3443         struct map_lookup *map;
3444         struct extent_map *em;
3445         int i;
3446         int ret = 0;
3447
3448         read_lock(&map_tree->map_tree.lock);
3449         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
3450         read_unlock(&map_tree->map_tree.lock);
3451
3452         if (!em) {
3453                 /*
3454                  * Might have been an unused block group deleted by the cleaner
3455                  * kthread or relocation.
3456                  */
3457                 spin_lock(&cache->lock);
3458                 if (!cache->removed)
3459                         ret = -EINVAL;
3460                 spin_unlock(&cache->lock);
3461
3462                 return ret;
3463         }
3464
3465         map = em->map_lookup;
3466         if (em->start != chunk_offset)
3467                 goto out;
3468
3469         if (em->len < length)
3470                 goto out;
3471
3472         for (i = 0; i < map->num_stripes; ++i) {
3473                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3474                     map->stripes[i].physical == dev_offset) {
3475                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3476                                            chunk_offset, length,
3477                                            is_dev_replace);
3478                         if (ret)
3479                                 goto out;
3480                 }
3481         }
3482 out:
3483         free_extent_map(em);
3484
3485         return ret;
3486 }
3487
3488 static noinline_for_stack
3489 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3490                            struct btrfs_device *scrub_dev, u64 start, u64 end,
3491                            int is_dev_replace)
3492 {
3493         struct btrfs_dev_extent *dev_extent = NULL;
3494         struct btrfs_path *path;
3495         struct btrfs_root *root = sctx->dev_root;
3496         struct btrfs_fs_info *fs_info = root->fs_info;
3497         u64 length;
3498         u64 chunk_offset;
3499         int ret = 0;
3500         int ro_set;
3501         int slot;
3502         struct extent_buffer *l;
3503         struct btrfs_key key;
3504         struct btrfs_key found_key;
3505         struct btrfs_block_group_cache *cache;
3506         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3507
3508         path = btrfs_alloc_path();
3509         if (!path)
3510                 return -ENOMEM;
3511
3512         path->reada = READA_FORWARD;
3513         path->search_commit_root = 1;
3514         path->skip_locking = 1;
3515
3516         key.objectid = scrub_dev->devid;
3517         key.offset = 0ull;
3518         key.type = BTRFS_DEV_EXTENT_KEY;
3519
3520         while (1) {
3521                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3522                 if (ret < 0)
3523                         break;
3524                 if (ret > 0) {
3525                         if (path->slots[0] >=
3526                             btrfs_header_nritems(path->nodes[0])) {
3527                                 ret = btrfs_next_leaf(root, path);
3528                                 if (ret < 0)
3529                                         break;
3530                                 if (ret > 0) {
3531                                         ret = 0;
3532                                         break;
3533                                 }
3534                         } else {
3535                                 ret = 0;
3536                         }
3537                 }
3538
3539                 l = path->nodes[0];
3540                 slot = path->slots[0];
3541
3542                 btrfs_item_key_to_cpu(l, &found_key, slot);
3543
3544                 if (found_key.objectid != scrub_dev->devid)
3545                         break;
3546
3547                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3548                         break;
3549
3550                 if (found_key.offset >= end)
3551                         break;
3552
3553                 if (found_key.offset < key.offset)
3554                         break;
3555
3556                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3557                 length = btrfs_dev_extent_length(l, dev_extent);
3558
3559                 if (found_key.offset + length <= start)
3560                         goto skip;
3561
3562                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3563
3564                 /*
3565                  * get a reference on the corresponding block group to prevent
3566                  * the chunk from going away while we scrub it
3567                  */
3568                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3569
3570                 /* some chunks are removed but not committed to disk yet,
3571                  * continue scrubbing */
3572                 if (!cache)
3573                         goto skip;
3574
3575                 /*
3576                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3577                  * to avoid deadlock caused by:
3578                  * btrfs_inc_block_group_ro()
3579                  * -> btrfs_wait_for_commit()
3580                  * -> btrfs_commit_transaction()
3581                  * -> btrfs_scrub_pause()
3582                  */
3583                 scrub_pause_on(fs_info);
3584                 ret = btrfs_inc_block_group_ro(root, cache);
3585                 if (!ret && is_dev_replace) {
3586                         /*
3587                          * If we are doing a device replace wait for any tasks
3588                          * that started dellaloc right before we set the block
3589                          * group to RO mode, as they might have just allocated
3590                          * an extent from it or decided they could do a nocow
3591                          * write. And if any such tasks did that, wait for their
3592                          * ordered extents to complete and then commit the
3593                          * current transaction, so that we can later see the new
3594                          * extent items in the extent tree - the ordered extents
3595                          * create delayed data references (for cow writes) when
3596                          * they complete, which will be run and insert the
3597                          * corresponding extent items into the extent tree when
3598                          * we commit the transaction they used when running
3599                          * inode.c:btrfs_finish_ordered_io(). We later use
3600                          * the commit root of the extent tree to find extents
3601                          * to copy from the srcdev into the tgtdev, and we don't
3602                          * want to miss any new extents.
3603                          */
3604                         btrfs_wait_block_group_reservations(cache);
3605                         btrfs_wait_nocow_writers(cache);
3606                         ret = btrfs_wait_ordered_roots(fs_info, -1,
3607                                                        cache->key.objectid,
3608                                                        cache->key.offset);
3609                         if (ret > 0) {
3610                                 struct btrfs_trans_handle *trans;
3611
3612                                 trans = btrfs_join_transaction(root);
3613                                 if (IS_ERR(trans))
3614                                         ret = PTR_ERR(trans);
3615                                 else
3616                                         ret = btrfs_commit_transaction(trans,
3617                                                                        root);
3618                                 if (ret) {
3619                                         scrub_pause_off(fs_info);
3620                                         btrfs_put_block_group(cache);
3621                                         break;
3622                                 }
3623                         }
3624                 }
3625                 scrub_pause_off(fs_info);
3626
3627                 if (ret == 0) {
3628                         ro_set = 1;
3629                 } else if (ret == -ENOSPC) {
3630                         /*
3631                          * btrfs_inc_block_group_ro return -ENOSPC when it
3632                          * failed in creating new chunk for metadata.
3633                          * It is not a problem for scrub/replace, because
3634                          * metadata are always cowed, and our scrub paused
3635                          * commit_transactions.
3636                          */
3637                         ro_set = 0;
3638                 } else {
3639                         btrfs_warn(fs_info, "failed setting block group ro, ret=%d\n",
3640                                    ret);
3641                         btrfs_put_block_group(cache);
3642                         break;
3643                 }
3644
3645                 btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
3646                 dev_replace->cursor_right = found_key.offset + length;
3647                 dev_replace->cursor_left = found_key.offset;
3648                 dev_replace->item_needs_writeback = 1;
3649                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
3650                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3651                                   found_key.offset, cache, is_dev_replace);
3652
3653                 /*
3654                  * flush, submit all pending read and write bios, afterwards
3655                  * wait for them.
3656                  * Note that in the dev replace case, a read request causes
3657                  * write requests that are submitted in the read completion
3658                  * worker. Therefore in the current situation, it is required
3659                  * that all write requests are flushed, so that all read and
3660                  * write requests are really completed when bios_in_flight
3661                  * changes to 0.
3662                  */
3663                 atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
3664                 scrub_submit(sctx);
3665                 mutex_lock(&sctx->wr_ctx.wr_lock);
3666                 scrub_wr_submit(sctx);
3667                 mutex_unlock(&sctx->wr_ctx.wr_lock);
3668
3669                 wait_event(sctx->list_wait,
3670                            atomic_read(&sctx->bios_in_flight) == 0);
3671
3672                 scrub_pause_on(fs_info);
3673
3674                 /*
3675                  * must be called before we decrease @scrub_paused.
3676                  * make sure we don't block transaction commit while
3677                  * we are waiting pending workers finished.
3678                  */
3679                 wait_event(sctx->list_wait,
3680                            atomic_read(&sctx->workers_pending) == 0);
3681                 atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
3682
3683                 scrub_pause_off(fs_info);
3684
3685                 btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
3686                 dev_replace->cursor_left = dev_replace->cursor_right;
3687                 dev_replace->item_needs_writeback = 1;
3688                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
3689
3690                 if (ro_set)
3691                         btrfs_dec_block_group_ro(root, cache);
3692
3693                 /*
3694                  * We might have prevented the cleaner kthread from deleting
3695                  * this block group if it was already unused because we raced
3696                  * and set it to RO mode first. So add it back to the unused
3697                  * list, otherwise it might not ever be deleted unless a manual
3698                  * balance is triggered or it becomes used and unused again.
3699                  */
3700                 spin_lock(&cache->lock);
3701                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3702                     btrfs_block_group_used(&cache->item) == 0) {
3703                         spin_unlock(&cache->lock);
3704                         spin_lock(&fs_info->unused_bgs_lock);
3705                         if (list_empty(&cache->bg_list)) {
3706                                 btrfs_get_block_group(cache);
3707                                 list_add_tail(&cache->bg_list,
3708                                               &fs_info->unused_bgs);
3709                         }
3710                         spin_unlock(&fs_info->unused_bgs_lock);
3711                 } else {
3712                         spin_unlock(&cache->lock);
3713                 }
3714
3715                 btrfs_put_block_group(cache);
3716                 if (ret)
3717                         break;
3718                 if (is_dev_replace &&
3719                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3720                         ret = -EIO;
3721                         break;
3722                 }
3723                 if (sctx->stat.malloc_errors > 0) {
3724                         ret = -ENOMEM;
3725                         break;
3726                 }
3727 skip:
3728                 key.offset = found_key.offset + length;
3729                 btrfs_release_path(path);
3730         }
3731
3732         btrfs_free_path(path);
3733
3734         return ret;
3735 }
3736
3737 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3738                                            struct btrfs_device *scrub_dev)
3739 {
3740         int     i;
3741         u64     bytenr;
3742         u64     gen;
3743         int     ret;
3744         struct btrfs_root *root = sctx->dev_root;
3745
3746         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
3747                 return -EIO;
3748
3749         /* Seed devices of a new filesystem has their own generation. */
3750         if (scrub_dev->fs_devices != root->fs_info->fs_devices)
3751                 gen = scrub_dev->generation;
3752         else
3753                 gen = root->fs_info->last_trans_committed;
3754
3755         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
3756                 bytenr = btrfs_sb_offset(i);
3757                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
3758                     scrub_dev->commit_total_bytes)
3759                         break;
3760
3761                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
3762                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
3763                                   NULL, 1, bytenr);
3764                 if (ret)
3765                         return ret;
3766         }
3767         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3768
3769         return 0;
3770 }
3771
3772 /*
3773  * get a reference count on fs_info->scrub_workers. start worker if necessary
3774  */
3775 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
3776                                                 int is_dev_replace)
3777 {
3778         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
3779         int max_active = fs_info->thread_pool_size;
3780
3781         if (fs_info->scrub_workers_refcnt == 0) {
3782                 if (is_dev_replace)
3783                         fs_info->scrub_workers =
3784                                 btrfs_alloc_workqueue("scrub", flags,
3785                                                       1, 4);
3786                 else
3787                         fs_info->scrub_workers =
3788                                 btrfs_alloc_workqueue("scrub", flags,
3789                                                       max_active, 4);
3790                 if (!fs_info->scrub_workers)
3791                         goto fail_scrub_workers;
3792
3793                 fs_info->scrub_wr_completion_workers =
3794                         btrfs_alloc_workqueue("scrubwrc", flags,
3795                                               max_active, 2);
3796                 if (!fs_info->scrub_wr_completion_workers)
3797                         goto fail_scrub_wr_completion_workers;
3798
3799                 fs_info->scrub_nocow_workers =
3800                         btrfs_alloc_workqueue("scrubnc", flags, 1, 0);
3801                 if (!fs_info->scrub_nocow_workers)
3802                         goto fail_scrub_nocow_workers;
3803                 fs_info->scrub_parity_workers =
3804                         btrfs_alloc_workqueue("scrubparity", flags,
3805                                               max_active, 2);
3806                 if (!fs_info->scrub_parity_workers)
3807                         goto fail_scrub_parity_workers;
3808         }
3809         ++fs_info->scrub_workers_refcnt;
3810         return 0;
3811
3812 fail_scrub_parity_workers:
3813         btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
3814 fail_scrub_nocow_workers:
3815         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3816 fail_scrub_wr_completion_workers:
3817         btrfs_destroy_workqueue(fs_info->scrub_workers);
3818 fail_scrub_workers:
3819         return -ENOMEM;
3820 }
3821
3822 static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
3823 {
3824         if (--fs_info->scrub_workers_refcnt == 0) {
3825                 btrfs_destroy_workqueue(fs_info->scrub_workers);
3826                 btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3827                 btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
3828                 btrfs_destroy_workqueue(fs_info->scrub_parity_workers);
3829         }
3830         WARN_ON(fs_info->scrub_workers_refcnt < 0);
3831 }
3832
3833 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
3834                     u64 end, struct btrfs_scrub_progress *progress,
3835                     int readonly, int is_dev_replace)
3836 {
3837         struct scrub_ctx *sctx;
3838         int ret;
3839         struct btrfs_device *dev;
3840         struct rcu_string *name;
3841
3842         if (btrfs_fs_closing(fs_info))
3843                 return -EINVAL;
3844
3845         if (fs_info->chunk_root->nodesize > BTRFS_STRIPE_LEN) {
3846                 /*
3847                  * in this case scrub is unable to calculate the checksum
3848                  * the way scrub is implemented. Do not handle this
3849                  * situation at all because it won't ever happen.
3850                  */
3851                 btrfs_err(fs_info,
3852                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
3853                        fs_info->chunk_root->nodesize, BTRFS_STRIPE_LEN);
3854                 return -EINVAL;
3855         }
3856
3857         if (fs_info->chunk_root->sectorsize != PAGE_SIZE) {
3858                 /* not supported for data w/o checksums */
3859                 btrfs_err(fs_info,
3860                            "scrub: size assumption sectorsize != PAGE_SIZE "
3861                            "(%d != %lu) fails",
3862                        fs_info->chunk_root->sectorsize, PAGE_SIZE);
3863                 return -EINVAL;
3864         }
3865
3866         if (fs_info->chunk_root->nodesize >
3867             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
3868             fs_info->chunk_root->sectorsize >
3869             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
3870                 /*
3871                  * would exhaust the array bounds of pagev member in
3872                  * struct scrub_block
3873                  */
3874                 btrfs_err(fs_info, "scrub: size assumption nodesize and sectorsize "
3875                            "<= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
3876                        fs_info->chunk_root->nodesize,
3877                        SCRUB_MAX_PAGES_PER_BLOCK,
3878                        fs_info->chunk_root->sectorsize,
3879                        SCRUB_MAX_PAGES_PER_BLOCK);
3880                 return -EINVAL;
3881         }
3882
3883
3884         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3885         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
3886         if (!dev || (dev->missing && !is_dev_replace)) {
3887                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3888                 return -ENODEV;
3889         }
3890
3891         if (!is_dev_replace && !readonly && !dev->writeable) {
3892                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3893                 rcu_read_lock();
3894                 name = rcu_dereference(dev->name);
3895                 btrfs_err(fs_info, "scrub: device %s is not writable",
3896                           name->str);
3897                 rcu_read_unlock();
3898                 return -EROFS;
3899         }
3900
3901         mutex_lock(&fs_info->scrub_lock);
3902         if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
3903                 mutex_unlock(&fs_info->scrub_lock);
3904                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3905                 return -EIO;
3906         }
3907
3908         btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
3909         if (dev->scrub_device ||
3910             (!is_dev_replace &&
3911              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
3912                 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
3913                 mutex_unlock(&fs_info->scrub_lock);
3914                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3915                 return -EINPROGRESS;
3916         }
3917         btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
3918
3919         ret = scrub_workers_get(fs_info, is_dev_replace);
3920         if (ret) {
3921                 mutex_unlock(&fs_info->scrub_lock);
3922                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3923                 return ret;
3924         }
3925
3926         sctx = scrub_setup_ctx(dev, is_dev_replace);
3927         if (IS_ERR(sctx)) {
3928                 mutex_unlock(&fs_info->scrub_lock);
3929                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3930                 scrub_workers_put(fs_info);
3931                 return PTR_ERR(sctx);
3932         }
3933         sctx->readonly = readonly;
3934         dev->scrub_device = sctx;
3935         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3936
3937         /*
3938          * checking @scrub_pause_req here, we can avoid
3939          * race between committing transaction and scrubbing.
3940          */
3941         __scrub_blocked_if_needed(fs_info);
3942         atomic_inc(&fs_info->scrubs_running);
3943         mutex_unlock(&fs_info->scrub_lock);
3944
3945         if (!is_dev_replace) {
3946                 /*
3947                  * by holding device list mutex, we can
3948                  * kick off writing super in log tree sync.
3949                  */
3950                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
3951                 ret = scrub_supers(sctx, dev);
3952                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3953         }
3954
3955         if (!ret)
3956                 ret = scrub_enumerate_chunks(sctx, dev, start, end,
3957                                              is_dev_replace);
3958
3959         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3960         atomic_dec(&fs_info->scrubs_running);
3961         wake_up(&fs_info->scrub_pause_wait);
3962
3963         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3964
3965         if (progress)
3966                 memcpy(progress, &sctx->stat, sizeof(*progress));
3967
3968         mutex_lock(&fs_info->scrub_lock);
3969         dev->scrub_device = NULL;
3970         scrub_workers_put(fs_info);
3971         mutex_unlock(&fs_info->scrub_lock);
3972
3973         scrub_put_ctx(sctx);
3974
3975         return ret;
3976 }
3977
3978 void btrfs_scrub_pause(struct btrfs_root *root)
3979 {
3980         struct btrfs_fs_info *fs_info = root->fs_info;
3981
3982         mutex_lock(&fs_info->scrub_lock);
3983         atomic_inc(&fs_info->scrub_pause_req);
3984         while (atomic_read(&fs_info->scrubs_paused) !=
3985                atomic_read(&fs_info->scrubs_running)) {
3986                 mutex_unlock(&fs_info->scrub_lock);
3987                 wait_event(fs_info->scrub_pause_wait,
3988                            atomic_read(&fs_info->scrubs_paused) ==
3989                            atomic_read(&fs_info->scrubs_running));
3990                 mutex_lock(&fs_info->scrub_lock);
3991         }
3992         mutex_unlock(&fs_info->scrub_lock);
3993 }
3994
3995 void btrfs_scrub_continue(struct btrfs_root *root)
3996 {
3997         struct btrfs_fs_info *fs_info = root->fs_info;
3998
3999         atomic_dec(&fs_info->scrub_pause_req);
4000         wake_up(&fs_info->scrub_pause_wait);
4001 }
4002
4003 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
4004 {
4005         mutex_lock(&fs_info->scrub_lock);
4006         if (!atomic_read(&fs_info->scrubs_running)) {
4007                 mutex_unlock(&fs_info->scrub_lock);
4008                 return -ENOTCONN;
4009         }
4010
4011         atomic_inc(&fs_info->scrub_cancel_req);
4012         while (atomic_read(&fs_info->scrubs_running)) {
4013                 mutex_unlock(&fs_info->scrub_lock);
4014                 wait_event(fs_info->scrub_pause_wait,
4015                            atomic_read(&fs_info->scrubs_running) == 0);
4016                 mutex_lock(&fs_info->scrub_lock);
4017         }
4018         atomic_dec(&fs_info->scrub_cancel_req);
4019         mutex_unlock(&fs_info->scrub_lock);
4020
4021         return 0;
4022 }
4023
4024 int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
4025                            struct btrfs_device *dev)
4026 {
4027         struct scrub_ctx *sctx;
4028
4029         mutex_lock(&fs_info->scrub_lock);
4030         sctx = dev->scrub_device;
4031         if (!sctx) {
4032                 mutex_unlock(&fs_info->scrub_lock);
4033                 return -ENOTCONN;
4034         }
4035         atomic_inc(&sctx->cancel_req);
4036         while (dev->scrub_device) {
4037                 mutex_unlock(&fs_info->scrub_lock);
4038                 wait_event(fs_info->scrub_pause_wait,
4039                            dev->scrub_device == NULL);
4040                 mutex_lock(&fs_info->scrub_lock);
4041         }
4042         mutex_unlock(&fs_info->scrub_lock);
4043
4044         return 0;
4045 }
4046
4047 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
4048                          struct btrfs_scrub_progress *progress)
4049 {
4050         struct btrfs_device *dev;
4051         struct scrub_ctx *sctx = NULL;
4052
4053         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
4054         dev = btrfs_find_device(root->fs_info, devid, NULL, NULL);
4055         if (dev)
4056                 sctx = dev->scrub_device;
4057         if (sctx)
4058                 memcpy(progress, &sctx->stat, sizeof(*progress));
4059         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
4060
4061         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
4062 }
4063
4064 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
4065                                u64 extent_logical, u64 extent_len,
4066                                u64 *extent_physical,
4067                                struct btrfs_device **extent_dev,
4068                                int *extent_mirror_num)
4069 {
4070         u64 mapped_length;
4071         struct btrfs_bio *bbio = NULL;
4072         int ret;
4073
4074         mapped_length = extent_len;
4075         ret = btrfs_map_block(fs_info, READ, extent_logical,
4076                               &mapped_length, &bbio, 0);
4077         if (ret || !bbio || mapped_length < extent_len ||
4078             !bbio->stripes[0].dev->bdev) {
4079                 btrfs_put_bbio(bbio);
4080                 return;
4081         }
4082
4083         *extent_physical = bbio->stripes[0].physical;
4084         *extent_mirror_num = bbio->mirror_num;
4085         *extent_dev = bbio->stripes[0].dev;
4086         btrfs_put_bbio(bbio);
4087 }
4088
4089 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
4090                               struct scrub_wr_ctx *wr_ctx,
4091                               struct btrfs_fs_info *fs_info,
4092                               struct btrfs_device *dev,
4093                               int is_dev_replace)
4094 {
4095         WARN_ON(wr_ctx->wr_curr_bio != NULL);
4096
4097         mutex_init(&wr_ctx->wr_lock);
4098         wr_ctx->wr_curr_bio = NULL;
4099         if (!is_dev_replace)
4100                 return 0;
4101
4102         WARN_ON(!dev->bdev);
4103         wr_ctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
4104         wr_ctx->tgtdev = dev;
4105         atomic_set(&wr_ctx->flush_all_writes, 0);
4106         return 0;
4107 }
4108
4109 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
4110 {
4111         mutex_lock(&wr_ctx->wr_lock);
4112         kfree(wr_ctx->wr_curr_bio);
4113         wr_ctx->wr_curr_bio = NULL;
4114         mutex_unlock(&wr_ctx->wr_lock);
4115 }
4116
4117 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
4118                             int mirror_num, u64 physical_for_dev_replace)
4119 {
4120         struct scrub_copy_nocow_ctx *nocow_ctx;
4121         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
4122
4123         nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
4124         if (!nocow_ctx) {
4125                 spin_lock(&sctx->stat_lock);
4126                 sctx->stat.malloc_errors++;
4127                 spin_unlock(&sctx->stat_lock);
4128                 return -ENOMEM;
4129         }
4130
4131         scrub_pending_trans_workers_inc(sctx);
4132
4133         nocow_ctx->sctx = sctx;
4134         nocow_ctx->logical = logical;
4135         nocow_ctx->len = len;
4136         nocow_ctx->mirror_num = mirror_num;
4137         nocow_ctx->physical_for_dev_replace = physical_for_dev_replace;
4138         btrfs_init_work(&nocow_ctx->work, btrfs_scrubnc_helper,
4139                         copy_nocow_pages_worker, NULL, NULL);
4140         INIT_LIST_HEAD(&nocow_ctx->inodes);
4141         btrfs_queue_work(fs_info->scrub_nocow_workers,
4142                          &nocow_ctx->work);
4143
4144         return 0;
4145 }
4146
4147 static int record_inode_for_nocow(u64 inum, u64 offset, u64 root, void *ctx)
4148 {
4149         struct scrub_copy_nocow_ctx *nocow_ctx = ctx;
4150         struct scrub_nocow_inode *nocow_inode;
4151
4152         nocow_inode = kzalloc(sizeof(*nocow_inode), GFP_NOFS);
4153         if (!nocow_inode)
4154                 return -ENOMEM;
4155         nocow_inode->inum = inum;
4156         nocow_inode->offset = offset;
4157         nocow_inode->root = root;
4158         list_add_tail(&nocow_inode->list, &nocow_ctx->inodes);
4159         return 0;
4160 }
4161
4162 #define COPY_COMPLETE 1
4163
4164 static void copy_nocow_pages_worker(struct btrfs_work *work)
4165 {
4166         struct scrub_copy_nocow_ctx *nocow_ctx =
4167                 container_of(work, struct scrub_copy_nocow_ctx, work);
4168         struct scrub_ctx *sctx = nocow_ctx->sctx;
4169         u64 logical = nocow_ctx->logical;
4170         u64 len = nocow_ctx->len;
4171         int mirror_num = nocow_ctx->mirror_num;
4172         u64 physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
4173         int ret;
4174         struct btrfs_trans_handle *trans = NULL;
4175         struct btrfs_fs_info *fs_info;
4176         struct btrfs_path *path;
4177         struct btrfs_root *root;
4178         int not_written = 0;
4179
4180         fs_info = sctx->dev_root->fs_info;
4181         root = fs_info->extent_root;
4182
4183         path = btrfs_alloc_path();
4184         if (!path) {
4185                 spin_lock(&sctx->stat_lock);
4186                 sctx->stat.malloc_errors++;
4187                 spin_unlock(&sctx->stat_lock);
4188                 not_written = 1;
4189                 goto out;
4190         }
4191
4192         trans = btrfs_join_transaction(root);
4193         if (IS_ERR(trans)) {
4194                 not_written = 1;
4195                 goto out;
4196         }
4197
4198         ret = iterate_inodes_from_logical(logical, fs_info, path,
4199                                           record_inode_for_nocow, nocow_ctx);
4200         if (ret != 0 && ret != -ENOENT) {
4201                 btrfs_warn(fs_info, "iterate_inodes_from_logical() failed: log %llu, "
4202                         "phys %llu, len %llu, mir %u, ret %d",
4203                         logical, physical_for_dev_replace, len, mirror_num,
4204                         ret);
4205                 not_written = 1;
4206                 goto out;
4207         }
4208
4209         btrfs_end_transaction(trans, root);
4210         trans = NULL;
4211         while (!list_empty(&nocow_ctx->inodes)) {
4212                 struct scrub_nocow_inode *entry;
4213                 entry = list_first_entry(&nocow_ctx->inodes,
4214                                          struct scrub_nocow_inode,
4215                                          list);
4216                 list_del_init(&entry->list);
4217                 ret = copy_nocow_pages_for_inode(entry->inum, entry->offset,
4218                                                  entry->root, nocow_ctx);
4219                 kfree(entry);
4220                 if (ret == COPY_COMPLETE) {
4221                         ret = 0;
4222                         break;
4223                 } else if (ret) {
4224                         break;
4225                 }
4226         }
4227 out:
4228         while (!list_empty(&nocow_ctx->inodes)) {
4229                 struct scrub_nocow_inode *entry;
4230                 entry = list_first_entry(&nocow_ctx->inodes,
4231                                          struct scrub_nocow_inode,
4232                                          list);
4233                 list_del_init(&entry->list);
4234                 kfree(entry);
4235         }
4236         if (trans && !IS_ERR(trans))
4237                 btrfs_end_transaction(trans, root);
4238         if (not_written)
4239                 btrfs_dev_replace_stats_inc(&fs_info->dev_replace.
4240                                             num_uncorrectable_read_errors);
4241
4242         btrfs_free_path(path);
4243         kfree(nocow_ctx);
4244
4245         scrub_pending_trans_workers_dec(sctx);
4246 }
4247
4248 static int check_extent_to_block(struct inode *inode, u64 start, u64 len,
4249                                  u64 logical)
4250 {
4251         struct extent_state *cached_state = NULL;
4252         struct btrfs_ordered_extent *ordered;
4253         struct extent_io_tree *io_tree;
4254         struct extent_map *em;
4255         u64 lockstart = start, lockend = start + len - 1;
4256         int ret = 0;
4257
4258         io_tree = &BTRFS_I(inode)->io_tree;
4259
4260         lock_extent_bits(io_tree, lockstart, lockend, &cached_state);
4261         ordered = btrfs_lookup_ordered_range(inode, lockstart, len);
4262         if (ordered) {
4263                 btrfs_put_ordered_extent(ordered);
4264                 ret = 1;
4265                 goto out_unlock;
4266         }
4267
4268         em = btrfs_get_extent(inode, NULL, 0, start, len, 0);
4269         if (IS_ERR(em)) {
4270                 ret = PTR_ERR(em);
4271                 goto out_unlock;
4272         }
4273
4274         /*
4275          * This extent does not actually cover the logical extent anymore,
4276          * move on to the next inode.
4277          */
4278         if (em->block_start > logical ||
4279             em->block_start + em->block_len < logical + len) {
4280                 free_extent_map(em);
4281                 ret = 1;
4282                 goto out_unlock;
4283         }
4284         free_extent_map(em);
4285
4286 out_unlock:
4287         unlock_extent_cached(io_tree, lockstart, lockend, &cached_state,
4288                              GFP_NOFS);
4289         return ret;
4290 }
4291
4292 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
4293                                       struct scrub_copy_nocow_ctx *nocow_ctx)
4294 {
4295         struct btrfs_fs_info *fs_info = nocow_ctx->sctx->dev_root->fs_info;
4296         struct btrfs_key key;
4297         struct inode *inode;
4298         struct page *page;
4299         struct btrfs_root *local_root;
4300         struct extent_io_tree *io_tree;
4301         u64 physical_for_dev_replace;
4302         u64 nocow_ctx_logical;
4303         u64 len = nocow_ctx->len;
4304         unsigned long index;
4305         int srcu_index;
4306         int ret = 0;
4307         int err = 0;
4308
4309         key.objectid = root;
4310         key.type = BTRFS_ROOT_ITEM_KEY;
4311         key.offset = (u64)-1;
4312
4313         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
4314
4315         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
4316         if (IS_ERR(local_root)) {
4317                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
4318                 return PTR_ERR(local_root);
4319         }
4320
4321         key.type = BTRFS_INODE_ITEM_KEY;
4322         key.objectid = inum;
4323         key.offset = 0;
4324         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
4325         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
4326         if (IS_ERR(inode))
4327                 return PTR_ERR(inode);
4328
4329         /* Avoid truncate/dio/punch hole.. */
4330         inode_lock(inode);
4331         inode_dio_wait(inode);
4332
4333         physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
4334         io_tree = &BTRFS_I(inode)->io_tree;
4335         nocow_ctx_logical = nocow_ctx->logical;
4336
4337         ret = check_extent_to_block(inode, offset, len, nocow_ctx_logical);
4338         if (ret) {
4339                 ret = ret > 0 ? 0 : ret;
4340                 goto out;
4341         }
4342
4343         while (len >= PAGE_SIZE) {
4344                 index = offset >> PAGE_SHIFT;
4345 again:
4346                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
4347                 if (!page) {
4348                         btrfs_err(fs_info, "find_or_create_page() failed");
4349                         ret = -ENOMEM;
4350                         goto out;
4351                 }
4352
4353                 if (PageUptodate(page)) {
4354                         if (PageDirty(page))
4355                                 goto next_page;
4356                 } else {
4357                         ClearPageError(page);
4358                         err = extent_read_full_page(io_tree, page,
4359                                                            btrfs_get_extent,
4360                                                            nocow_ctx->mirror_num);
4361                         if (err) {
4362                                 ret = err;
4363                                 goto next_page;
4364                         }
4365
4366                         lock_page(page);
4367                         /*
4368                          * If the page has been remove from the page cache,
4369                          * the data on it is meaningless, because it may be
4370                          * old one, the new data may be written into the new
4371                          * page in the page cache.
4372                          */
4373                         if (page->mapping != inode->i_mapping) {
4374                                 unlock_page(page);
4375                                 put_page(page);
4376                                 goto again;
4377                         }
4378                         if (!PageUptodate(page)) {
4379                                 ret = -EIO;
4380                                 goto next_page;
4381                         }
4382                 }
4383
4384                 ret = check_extent_to_block(inode, offset, len,
4385                                             nocow_ctx_logical);
4386                 if (ret) {
4387                         ret = ret > 0 ? 0 : ret;
4388                         goto next_page;
4389                 }
4390
4391                 err = write_page_nocow(nocow_ctx->sctx,
4392                                        physical_for_dev_replace, page);
4393                 if (err)
4394                         ret = err;
4395 next_page:
4396                 unlock_page(page);
4397                 put_page(page);
4398
4399                 if (ret)
4400                         break;
4401
4402                 offset += PAGE_SIZE;
4403                 physical_for_dev_replace += PAGE_SIZE;
4404                 nocow_ctx_logical += PAGE_SIZE;
4405                 len -= PAGE_SIZE;
4406         }
4407         ret = COPY_COMPLETE;
4408 out:
4409         inode_unlock(inode);
4410         iput(inode);
4411         return ret;
4412 }
4413
4414 static int write_page_nocow(struct scrub_ctx *sctx,
4415                             u64 physical_for_dev_replace, struct page *page)
4416 {
4417         struct bio *bio;
4418         struct btrfs_device *dev;
4419         int ret;
4420
4421         dev = sctx->wr_ctx.tgtdev;
4422         if (!dev)
4423                 return -EIO;
4424         if (!dev->bdev) {
4425                 btrfs_warn_rl(dev->dev_root->fs_info,
4426                         "scrub write_page_nocow(bdev == NULL) is unexpected");
4427                 return -EIO;
4428         }
4429         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
4430         if (!bio) {
4431                 spin_lock(&sctx->stat_lock);
4432                 sctx->stat.malloc_errors++;
4433                 spin_unlock(&sctx->stat_lock);
4434                 return -ENOMEM;
4435         }
4436         bio->bi_iter.bi_size = 0;
4437         bio->bi_iter.bi_sector = physical_for_dev_replace >> 9;
4438         bio->bi_bdev = dev->bdev;
4439         ret = bio_add_page(bio, page, PAGE_SIZE, 0);
4440         if (ret != PAGE_SIZE) {
4441 leave_with_eio:
4442                 bio_put(bio);
4443                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
4444                 return -EIO;
4445         }
4446
4447         if (btrfsic_submit_bio_wait(WRITE_SYNC, bio))
4448                 goto leave_with_eio;
4449
4450         bio_put(bio);
4451         return 0;
4452 }